Fetal Defects

Adrenogenital Syndrome

Congenital adrenal hyperplasia, unlike all other conditions responsible for the appearance of ambiguous genitalia in the newborn, may be life threatening because of a lack of synthesis of specific adrenal steroids. Prompt diagnosis and appropriate therapy are essential. With early treatment, normal external genitalia and fertility can be achieved. The manifestations of the adrenogenital syndrome in the 46,XX individual are most easily understood by examining the simplified biosynthetic pathways of mineralocorticoid, glucocorticoid, and sex steroids ( Figure 2.1 ). Two enzymes, 21 hydroxylase and 11β-hydroxylase, participate in the formation of the glucocorticoids desoxycorticosterone and cortisol and the mineralocorticoid aldosterone, but are unnecessary for synthesis of the sex steroids testosterone, estrone, and estradiol. Deficiency of either enzyme in the 46,XX female leads to elevated adrenocorticotropic hormone (ACTH) products and hence elevated levels of testosterone and other strongly androgenic intermediates, which may result in sexual ambiguity or marked virilization of the newborn’s external genitalia ( Table 2.4 ).

Biosynthesis of mineralocorticoids, glucocorticoids, and sex steroids.

Table 2.4

Forms of Adrenal Hyperplasia Affecting the External Genitalia

Deficiency	Syndrome	Ambiguous Genitalia	Postnatal Virilization
STAR protein	—	Males
3β-Hydroxysteroid dehydrogenase	Classic	Males	Yes
	Non-classic	No	Yes
17α-Hydroxylase	—	Males	No
21-Hydroxylase	Salt wasting	Females	Yes
	Simple virilizing	Females	Yes
	Non-classic	No	Yes
11β-Hydroxylase	Classic	Females	Yes
	Non-classic	No	Yes

 

3β-Hydroxysteroid dehydrogenase is required for testosterone formation. In its absence, the principal androgen to form is the weak androgen dehydroepiandrosterone (DHEA), which has 1/20 the potency of testosterone. Patients with deficiency of this enzyme, therefore, show signs of no more than mild virilization, usually with clitoral hypertrophy but not with labial fusion or anterior displacement of the urethral orifice.

21-Hydroxylase deficiency is inherited as an autosomal recessive trait caused by abnormalities of the CYP21A2 gene on chromosome 6 (which encodes for cytochrome P450, family 21). It accounts for more than 95% of cases of congenital adrenal hyperplasia, occurring once in 15,000 births, and is especially high in Ashkenazi Jews (1 : 27 live births). The clinical manifestation of classic congenital adrenogenital syndrome depends upon inactivation of the normally expressed copy of the CYP21A2 gene. In three-quarters of cases the cause is rearranged inactive elements of a homologous nonexpressed pseudogene, CYP21A1P . Deletion of the CYP21A1 gene itself causes the remaining cases. If the allele carries a defect encoding for a mild defect, then the child will develop a non-classic form of adrenal hyperplasia, which by definition occurs after birth and is never associated with genital ambiguity. This latter syndrome is common, occurring in 1% of all women, and is the major cause of adult-onset virilism.

The extent of virilization in genetic females with adrenogenital syndrome depends upon the timing in fetal life when androgen excess begins. If the onset begins after week 16 of gestation, the clitoris may be enlarged. If earlier, the vagina and urethra may open into a common urogenital sinus. More marked clitoral enlargement and an opening of the urogenital sinus at the clitoral base may mimic penile hypospadias and suggest an even earlier temporal effect. On occasion, the changes have been of such severity that the female infants have been misdiagnosed as cryptorchid males with or without hypospadias. Gonadal tumor development in genetic females with adrenogenital syndrome is rare.

Males who have the adrenogenital syndrome show no evidence of genital ambiguity, but may have an enlarged phallus and a hyperpigmented rugated scrotum. Clinically detectable bilateral testicular nodules occasionally develop during childhood or young adulthood and must be distinguished from true Leydig cell tumors ( Figure 2.2 ). Usually the cells are composed of interstitial cells larger than Leydig cells, secrete cortisol, and respond to treatment with the adrenolytic agent o,p′-DDD (mitotane), indicative that these cells are adrenal or adrenal like in origin. Bilaterality and decreasing tumor size after corticosteroid therapy are features indicative that this testicular ‘tumor’ of the adrenogenital syndrome is hyperplastic rather than neoplastic.

Interstitial cell tumor of adrenogenital syndrome. The tumor cells with vacuolated clear cytoplasm, which lie adjacent to immature seminiferous tubules, resemble adrenocortical cells more closely than Leydig cells.

Maternal Influence

Primary Gonadal Defects

A primary defect of the gonad in an XY karyotype individual may lead to male pseudohermaphroditism by any one of the following mechanisms: regression (destruction) of the gonads or their anlage during intrauterine life; agenesis of the Leydig cells; a specific enzymatic defect in testosterone, dihydrotestosterone synthesis, or receptors to these hormones; or a defect in elaboration or action of AMH.

Testicular Regression Syndrome

Testicular regression syndrome follows the irreparable destruction of both testes at a critical stage of fetal development in an XY individual, with resulting endocrine disturbances. Unilateral testicular destruction does not result in the syndrome.

The phenotype of an affected individual with testicular regression syndrome reflects the specific stage of fetal development during which the testes were damaged. In general, gonadal regression that occurs during embryonic life, before the elaboration of AMH and/or androgenic steroids by the testes, leads to a female phenotype. Regression of the testes during late embryonic through mid-fetal life permits a masculine phenotype ( Figure 2.3 ). Testicular regression has a variety of etiologies, as diverse as inherited genetic defect, intrauterine infection, or infarction. The heterogeneous presentations of this syndrome and its relative rarity have led to numerous and sometimes confusing terms for this disorder, including: true agonadism, testicular dysgenesis, rudimentary testis, vanishing testis, and complete bilateral anorchia. Pure gonadal dysgenesis (Swyer syndrome) has been used to designate some forms of the testicular regression syndrome, but this term is nonspecific and thus best avoided.

Testicular regression syndrome. The phenotypic appearance of the internal genitalia abnormalities relates to the time during embryogenesis when the normal development of the genital tract was damaged.

At one end of the testicular regression syndrome spectrum, the internal genitalia and gonads are absent and the external genitalia are female. Presumably, the urogenital ridge was destroyed in its entirety during early embryonic life, even before the müllerian ducts began to differentiate (prior to day 42). At the other end of the spectrum, which approximates the endpoint of normal genital development, the patients are phenotypic males with infantile to nearly normal male external genitalia, normally differentiated wolffian duct structures, and completely inhibited müllerian duct development. Often in these cases, no gonadal tissue is identified. However, there is sometimes a focus of vascularized fibrosis (85%), hemorrhage or hemosiderin deposition (70%), and calcification (60%) or giant cells at the expected site of the gonad, which is near the residual vas deferens or epididymis ( Figure 2.4 ). Occasionally, atrophic seminiferous tubules may be found amidst the fibrous stroma. Testicular regression presumably develops during the late fetal period (after 120 days) when müllerian structures have already atrophied under the influence of AMH, and testosterone and dihydrotestosterone have exerted a major influence on the normal development of internal and external genitalia, respectively. Torsion and infarction of improperly descended testes have been suggested.

Testicular regression syndrome. Vascularized fibrosis, hemosiderin deposition, and calcification are seen at the expected site of both gonads.

Intermediate in the spectrum of this disorder are patients with ambiguous genitalia and various combinations of wolffian and/or müllerian duct development. Testes that regress during the late embryonic period (days 43–59) usually secrete insufficient testosterone to affect the wolffian duct. The production of AMH is variable, resulting in poorly differentiated or rudimentary müllerian structures (incomplete inhibition). In the absence of systemic androgens, the external genitalia appear female.

Regression of the testes during the early fetal period (days 59–84), which is after Sertoli cell (AMH) and Leydig cell (testosterone) functions have begun or are about to begin, results in an individual with ambiguous external genitalia. Various combinations of wolffian and müllerian structures develop depending on the duration of androgen secretion and müllerian inhibition.

Regression of the testes during the mid-fetal period (days 84–120) results in more advanced masculinization of the external genitalia, although degrees of ambiguity are usually present. Since müllerian duct inhibition is normally completed by day 80, the müllerian structures will have been suppressed and wolffian structures develop.

Defect in Müllerian Inhibiting System (AMH and its Receptors)

The persistent müllerian duct syndrome, also known as ‘hernia uteri inguinalis,’ is a rare form of male pseudohermaphroditism where müllerian duct structures persist in 46,XY phenotypic males ( Figure 2.5 ). Most patients present when young with unilateral or bilateral cryptorchid testes, normal or almost normal male external genitalia, and an inguinal hernia into which prolapses an infantile uterus and fallopian tubes. Some patients may be older. The testes are histologically normal, wolffian duct structures are developed, the pubertal development is normal, and a rare patient has been fertile. Treatment is surgical, consisting of orchiopexy and herniorrhaphy with hysterectomy and bilateral salpingectomy.

Uterus in persistent müllerian duct syndrome.

If at operation any patient has a streak gonad or a tumor rather than bilateral testes, the diagnosis of mixed gonadal dysgenesis should be considered. In most cases of persistent müllerian duct syndrome, the vas deferens is embedded in the wall of the upper vagina and sometimes the müllerian structures must be left intact to preserve the vas deferens. Malignant testicular tumors have been reported in the very rare cases of adult patients with persistent müllerian duct syndrome and uncorrected cryptorchid testes.

Persistent müllerian duct syndrome is a heterogeneous group of disorders caused by at least two different defects in the müllerian inhibiting system. The most common is a defect in the anti-müllerian hormone gene, AMH (the protein is also called MIS). The next most common is a defective AMH type II receptor. The effect of these abnormalities is that some patients produce no biologically functional AMH, whereas others who produce normal amounts of biologically active AMH have end-organ insensitivity or an abnormality of the timing of AMH secretion. On rare occasion, a germ cell tumor may develop in the gonad, and, exceptionally, a müllerian-type tumor develops in the genital tract.

End-Organ Defects

The normal development of the wolffian duct derivatives and the external genitalia requires that these structures be responsive to androgen and that the enzyme 5α-reductase be present in the anlage of the prostate and external genitalia to convert testosterone to dihydrotestosterone. A molecular defect of the androgen receptor system (e.g., unstable androgen receptor or lack of androgen receptor) leads to impaired development of both wolffian duct structures and external genitalia in 46,XY individuals. If only 5α-reductase is absent or defective, the abnormalities in the reproductive tract are confined to the external genitalia and prostate.

Androgen Receptor Disorders (Androgen Insensitivity Syndromes)

Disordered androgen receptor function results in various phenotypes, which range from phenotypic women with intra-abdominal testes, to individuals with ambiguous genitalia, and to phenotypic men with minimal clinical abnormalities. One classification scheme lists four categories, which are in order of increasing virilization (decreasing feminization):

• 1.
  

  Complete testicular feminization

  
  
• 2.
  

  Incomplete testicular feminization

  
  
• 3.
  

  Reifenstein phenotype: gynecomastia and hypospadias

  
  
• 4.
  

  Infertile and/or undervirilized man.

About 70% of cases share an X-linked recessive inheritance through the carrier mothers, the result of mutational defects in the androgen receptor gene, which is in the X chromosome’s long arm. In another 30%, the mutation arises de novo . Other genetic mutations are known, many of which are limited to individual families. These mutations may lead to functional absence of the androgen receptor because the primary sequences of the gene are affected. These patients generally present as complete testicular feminization. The more common defect results from single amino acid substitutions and is associated with the various other forms of the disease as described below. In rare patients the androgen receptor disorder occurs in combination with other unusual karyotypes, e.g., 47,XXY and 47,XYY.

Complete Androgen Receptor Insufficiency (Complete Testicular Feminization).

Complete testicular feminization, the most common form of male pseudohermaphroditism, occurs in 1 : 20,000 newborns. The external genitalia are phenotypically female ( Figure 2.6 ) and, for this reason, the condition is rarely diagnosed before puberty unless an inguinal hernia or labial mass is encountered or unless the disease is known to be familial. Primary amenorrhea is the most common complaint leading to evaluation and subsequent diagnosis. The medical history usually reveals that breast develop­ment occurred as expected at puberty, but remains in the pubertal state ( Figure 2.7 ). Pubic and axillary hair is scant ( Figure 2.8 ) and the vagina is shortened. The epididymides are usually cystic and not connected to the testes. The vasa differentia, seminal vesicles, and prostate are absent. As a rule, both the cervix and the uterine corpus are absent. Fallopian tube fragments are found in one-third of cases. The testes are cryptorchid and may be located in the inguinal canal, the pelvis, or rarely the labia.

‘Normal’ phenotypic feminine genitalia in androgen insensitivity syndrome.

Immature breast development and lack of axillary hair in androgen insensitivity syndrome.

Lack of pubic hair in androgen insensitivity syndrome.

In the complete or almost complete form of the syndrome, the individual exhibits a female gender identity with normal extragenital erotogenic sensitivity and normal maternal attitude, emphasizing the need to support the patient as a woman, even with reconstructive surgery. This condition should be differentiated from defects in steroidogenic factor-1 mutations (XY, sex reversal with androgen insensitivity-like features) with which it can be confused.

The gonads in infants and young children are relatively normal but, by age 5 years, they show abnormalities. By young adulthood, the gonad is often involved with benign or malignant tumors as described later. If tumors are not present by this age, the gonad is usually small and on section is tan to brown and traversed by thin white bands ( Figure 2.9 ). Microscopic examination of the testicular parenchyma discloses immature seminiferous tubules. At earlier ages, the tubules may be clustered in small aggregates ( Figure 2.10 ), but with time they become more sparsely distributed ( Figure 2.11 ). Spermatogonia may be present, but spermatogenesis is absent. The number of spermatogonia found is also age dependent, diminishing as the patient ages. The interstitium, which resembles ovarian stroma, is usually abundant at an early age and over time often becomes more fibrous ( Figure 2.12 ). Fetal-type Leydig cells may be abundant. The Leydig cells in individuals with testicular feminization have an ultrastructure typical of cells involved in active hormone synthesis and the systemic androgen levels in these individuals are typically elevated. These findings indicate that the pathologic defect in the testicular feminization syndrome is an end-organ defect and not lack of hormone production by the testes.

Testis in androgen insensitivity syndrome without tumor.

Androgen insensitivity syndrome. Immature seminiferous tubules, numerous Leydig cells, and rare foci of immature ovarian-type stroma constitute the testis.

Androgen insensitivity syndrome. Scattered immature seminiferous tubules are embedded in the dense ovarian-type cortical stroma present in the testis.

Androgen insensitivity syndrome, gonad in an older patient. Dense ovarian-type cortical stroma with extremely rare scattered immature seminiferous tubules constitute the testis.

Most testes of affected individuals contain multiple benign nodules that are discrete, firm, yellow to brown, and bulge above the sectioned surface ( Figure 2.13 ). These can be hamartomatous (e.g., Sertoli cell adenoma) or neoplastic (e.g., dysgerminoma or gonadoblastoma like). One finding we have seen characteristically is a 1–2 cm firm white nodule of hyalinized smooth muscle leiomyoma-like tissue that is usually present at one pole of the testis ( Figure 2.14 ). Reactivity for smooth muscle actin confirms its smooth muscle origin ( Figure 2.15 ). Additionally, hamartomatous nodules are present, usually bilaterally, in virtually every case. The typical size varies from 1 mm to 1 cm, but occasionally up to 4 cm. The bulk of the nodule consists of seminiferous tubules lacking lumina ( Figure 2.16 ). Spermatogonia may be present ( Figure 2.17 ). The seminiferous tubules located outside the nodules have a lamina propria that is of normal thickness in prepubertal testes, but thickened and hyalinized in the adult. Sertoli cell adenomas, which average 3 cm in diameter, but range to 25 cm ( Figure 2.18 ), are hamartomas composed predominantly or exclusively of closely packed immature seminiferous tubules lacking lumina and lined by immature, uniform Sertoli cells ( Figure 2.19 ), some with germ cells ( Figure 2.20 ). The interstitium in the testes of affected patients often resembles ovarian stroma, and frequently contains Leydig cells ( Figure 2.10 ). On rare occasion, Leydig cell nodules form, and have been considered benign tumors ( Figure 2.21 ). Even though tumors have been reported occasionally as malignant, none has shown evidence of invasion or dissemination grossly or microscopically. In summary, the name applied to each type of nodule is somewhat arbitrary and depends largely upon the types of component present as well as their number and size. Most nodules are classified as hamartomas, Sertoli cell adenomas, or rarely as Leydig cell tumors.

Androgen insensitivity syndrome. Several small yellowish Sertoli cell adenomas are present throughout the specimen. The large white mass at the inferior pole may represent a hypertrophied gubernaculum testis or a leiomyoma present since birth.

Nodule of hypertrophied gubernaculum in androgen insensitivity syndrome.

(A) Androgen insensitivity syndrome with Sertoli adenoma (right) and hypertrophied gubernaculum (left). The adenoma expresses AMH (B) , and smooth muscle actin is positive in the gubernaculum (C) .

Sertoli cell adenoma in androgen insensitivity syndrome. The tubules lack lumens.

Seminiferous tubules with occasional spermatogonia in androgen insensitivity syndrome.

Giant Sertoli cell adenoma.

Interface of Sertoli cell adenoma (right) and adjacent degenerative seminiferous tubules (left) in androgen insensitivity syndrome.

Germ cells in Sertoli cell adenoma.

Leydig cell tumor in androgen insensitivity syndrome. Detail of a well-circumscribed gross nodule showing sheets of cells with large central nucleus and copious cytoplasm.

Malignant gonadal tumors develop with increasing frequency with age in patients with testicular feminization. Seminoma is the most commonly encountered gonadal malignancy in this syndrome. Intratubular germ cell neoplasia is sometimes seen, either independently or in association with seminoma ( Figures 2.22 and 2.23 ). Other malignant germ cell tumors and malignant sex cord tumors are also encountered rarely. Unlike mixed gonadal dysgenesis in which tumors develop in young individuals, the risk of malignancy in patients with testicular feminization is only 4% by the age of 25 years, but reaches 33% by 50 years. Since malignant tumors rarely develop before completion of puberty, castration can usually be delayed until after adolescence, thus permitting the patient to undergo normal pubertal development with spontaneous female secondary sex characteristics.

Seminoma in androgen insensitivity syndrome.

Seminoma in androgen insensitivity syndrome. Detail of neoplastic germ cells surrounded by fibrous stroma invested with numerous lymphocytes.

Partial Androgen Receptor Insufficiency (Incomplete Testicular Feminization).

About 10–50% of patients with the androgen insensitivity syndrome have an incomplete variant. The clinical manifestations vary depending on the classification system used. If restricted, it resembles complete testicular feminization except that there is partial fusion of the labioscrotal folds and usually some clitoromegaly at birth. If inclusive of all forms of the androgen insensitivity syndrome that are not considered complete testicular feminization, then greater percentages of patients will look and be raised as males. Viewed broadly, patients with partial androgen receptor insufficiency form one of the largest groups of intersex patients born with male sex ambiguity. Like the complete form, underdeveloped wolffian duct derivatives are often present. If the diagnosis is established during childhood, gonadectomy should be performed before puberty, since disfiguring virilization may accompany breast development at puberty. Estrogen therapy should be given at the appropriate time to initiate feminization. The pathologic findings are those described for the complete form of testicular feminization.

Other Forms.

Reifenstein syndrome, infertile male syndrome, and undervirilized male syndrome are other forms of incomplete androgen insensitivity in which the phenotype is male. There are few reports describing the microscopic findings of the gonads.

• •
  

  Patients with Reifenstein syndrome usually present with gynecomastia and severe hypospadias, like children or teenagers with perineoscrotal hypospadias. However, the phenotypic spectrum is wide, even within the same affected family with a single androgen receptor abnormality in all affected family members. Additional abnormalities include female habitus, azoospermia, cryptorchism, and hypoplasia or absence of wolffian duct structures.

  
  
• •
  

  Infertile male syndrome is a rare androgen receptor defect characterized by a phenotypically normal man with infertility caused by azoospermia.

  
  
• •
  

  In the undervirilized male syndrome, the individual is a male with gynecomastia, a small penis, decreased beard and body hair, a normal male urethra, a normal sperm density, and an identifiable androgen receptor defect. Most affected individuals are infertile.

Adrenogenital Syndrome

Congenital adrenal hyperplasia, unlike all other conditions responsible for the appearance of ambiguous genitalia in the newborn, may be life threatening because of a lack of synthesis of specific adrenal steroids. Prompt diagnosis and appropriate therapy are essential. With early treatment, normal external genitalia and fertility can be achieved. The manifestations of the adrenogenital syndrome in the 46,XX individual are most easily understood by examining the simplified biosynthetic pathways of mineralocorticoid, glucocorticoid, and sex steroids ( Figure 2.1 ). Two enzymes, 21 hydroxylase and 11β-hydroxylase, participate in the formation of the glucocorticoids desoxycorticosterone and cortisol and the mineralocorticoid aldosterone, but are unnecessary for synthesis of the sex steroids testosterone, estrone, and estradiol. Deficiency of either enzyme in the 46,XX female leads to elevated adrenocorticotropic hormone (ACTH) products and hence elevated levels of testosterone and other strongly androgenic intermediates, which may result in sexual ambiguity or marked virilization of the newborn’s external genitalia ( Table 2.4 ).

Biosynthesis of mineralocorticoids, glucocorticoids, and sex steroids.

3β-Hydroxysteroid dehydrogenase is required for testosterone formation. In its absence, the principal androgen to form is the weak androgen dehydroepiandrosterone (DHEA), which has 1/20 the potency of testosterone. Patients with deficiency of this enzyme, therefore, show signs of no more than mild virilization, usually with clitoral hypertrophy but not with labial fusion or anterior displacement of the urethral orifice.

21-Hydroxylase deficiency is inherited as an autosomal recessive trait caused by abnormalities of the CYP21A2 gene on chromosome 6 (which encodes for cytochrome P450, family 21). It accounts for more than 95% of cases of congenital adrenal hyperplasia, occurring once in 15,000 births, and is especially high in Ashkenazi Jews (1 : 27 live births). The clinical manifestation of classic congenital adrenogenital syndrome depends upon inactivation of the normally expressed copy of the CYP21A2 gene. In three-quarters of cases the cause is rearranged inactive elements of a homologous nonexpressed pseudogene, CYP21A1P . Deletion of the CYP21A1 gene itself causes the remaining cases. If the allele carries a defect encoding for a mild defect, then the child will develop a non-classic form of adrenal hyperplasia, which by definition occurs after birth and is never associated with genital ambiguity. This latter syndrome is common, occurring in 1% of all women, and is the major cause of adult-onset virilism.

The extent of virilization in genetic females with adrenogenital syndrome depends upon the timing in fetal life when androgen excess begins. If the onset begins after week 16 of gestation, the clitoris may be enlarged. If earlier, the vagina and urethra may open into a common urogenital sinus. More marked clitoral enlargement and an opening of the urogenital sinus at the clitoral base may mimic penile hypospadias and suggest an even earlier temporal effect. On occasion, the changes have been of such severity that the female infants have been misdiagnosed as cryptorchid males with or without hypospadias. Gonadal tumor development in genetic females with adrenogenital syndrome is rare.

Males who have the adrenogenital syndrome show no evidence of genital ambiguity, but may have an enlarged phallus and a hyperpigmented rugated scrotum. Clinically detectable bilateral testicular nodules occasionally develop during childhood or young adulthood and must be distinguished from true Leydig cell tumors ( Figure 2.2 ). Usually the cells are composed of interstitial cells larger than Leydig cells, secrete cortisol, and respond to treatment with the adrenolytic agent o,p′-DDD (mitotane), indicative that these cells are adrenal or adrenal like in origin. Bilaterality and decreasing tumor size after corticosteroid therapy are features indicative that this testicular ‘tumor’ of the adrenogenital syndrome is hyperplastic rather than neoplastic.

Interstitial cell tumor of adrenogenital syndrome. The tumor cells with vacuolated clear cytoplasm, which lie adjacent to immature seminiferous tubules, resemble adrenocortical cells more closely than Leydig cells.

Placental Aromatase Defect

Placental aromatase deficiency is a rare cause of maternal virilization during pregnancy and pseudohermaphroditism of the female fetus. Mutations in the aromatase gene, CYP19A1 , which causes abnormally low conversion of androstenedione to 17β-estradiol and estrone, result in virilization of the mother and her female fetus because potent androgens that are not converted to estrogens accumulate. The mothers usually show the onset of progressive virilization during the third trimester. The male fetus has normal genitalia.

Maternal Ingestion of Progestins or Androgens

Maternal ingestion of synthetic progestins was implicated as a cause of female pseudohermaphroditism in the late 1950s when such treatment was employed for threatened or habitual abortion. Subsequently, progestins have also been implicated in the development of hypospadias in male offspring. Most cases of female pseudohermaphroditism in this category developed after maternal ingestion of Norlutin (17α-ethinyl-19-nortestosterone), less often with ethisterone (17α-ethinyltestosterone), and occasionally after the ingestion of Enovid, diethylstilbestrol, androgens, or the intramuscular administration of progesterone.

Masculinization usually consists of phallic enlargement and variable degrees of labioscrotal fusion, depending on the time during gestation when the therapy was administered. Although the degree of masculinization is usually less than that associated with the adrenogenital syndrome, the sexual ambiguity in female infants has been of such severity in some instances as to result in male sex assignment. The degree of virilization does not progress with age. The gonads and internal genital organs are unaffected, and ovulation, menstruation, and normal secondary female characteristics appear at puberty.

Maternal Virilizing Lesions

A variety of benign and malignant tumors and tumor-like conditions, primary as well as metastatic to the ovary, have been associated with virilization of the mother and/or her female offspring. The luteoma of pregnancy and pronounced theca–lutein cysts (hyperreactio luteinalis) are the most common lesions that cause maternal virilization during pregnancy. These are benign hyperplastic lesions of the ovaries encountered most often as an incidental finding at the time of cesarean section or postpartum sterilization, usually in women who are multiparous. Elevated levels of human chorionic gonadotropin (hCG) induce hyperplasia of theca–lutein or stroma–lutein cells, which are responsible for the production of androgen (principally androstene­dione). Some female infants become masculinized, with mild enlargement of the clitoris and occasionally minimal degrees of labioscrotal fusion or rugate, hyperpigmented (‘scrotal’) labia. The nature of these changes indicates that the ovarian nodules do not function until the second half of gestation, which agrees with the occasional onset of masculinization in the mother during the third trimester.

Elevated plasma and tissue levels of testosterone, dihydrotestosterone, androstenedione, and DHEA have been detected in virilized patients. The plasma levels return to normal once the tumor is extirpated. Even without treatment, the nodules regress and disappear soon after delivery. Rarely, a functional luteoma may recur during a subsequent pregnancy.

Testicular Regression Syndrome

Testicular regression syndrome follows the irreparable destruction of both testes at a critical stage of fetal development in an XY individual, with resulting endocrine disturbances. Unilateral testicular destruction does not result in the syndrome.

The phenotype of an affected individual with testicular regression syndrome reflects the specific stage of fetal development during which the testes were damaged. In general, gonadal regression that occurs during embryonic life, before the elaboration of AMH and/or androgenic steroids by the testes, leads to a female phenotype. Regression of the testes during late embryonic through mid-fetal life permits a masculine phenotype ( Figure 2.3 ). Testicular regression has a variety of etiologies, as diverse as inherited genetic defect, intrauterine infection, or infarction. The heterogeneous presentations of this syndrome and its relative rarity have led to numerous and sometimes confusing terms for this disorder, including: true agonadism, testicular dysgenesis, rudimentary testis, vanishing testis, and complete bilateral anorchia. Pure gonadal dysgenesis (Swyer syndrome) has been used to designate some forms of the testicular regression syndrome, but this term is nonspecific and thus best avoided.

Testicular regression syndrome. The phenotypic appearance of the internal genitalia abnormalities relates to the time during embryogenesis when the normal development of the genital tract was damaged.

At one end of the testicular regression syndrome spectrum, the internal genitalia and gonads are absent and the external genitalia are female. Presumably, the urogenital ridge was destroyed in its entirety during early embryonic life, even before the müllerian ducts began to differentiate (prior to day 42). At the other end of the spectrum, which approximates the endpoint of normal genital development, the patients are phenotypic males with infantile to nearly normal male external genitalia, normally differentiated wolffian duct structures, and completely inhibited müllerian duct development. Often in these cases, no gonadal tissue is identified. However, there is sometimes a focus of vascularized fibrosis (85%), hemorrhage or hemosiderin deposition (70%), and calcification (60%) or giant cells at the expected site of the gonad, which is near the residual vas deferens or epididymis ( Figure 2.4 ). Occasionally, atrophic seminiferous tubules may be found amidst the fibrous stroma. Testicular regression presumably develops during the late fetal period (after 120 days) when müllerian structures have already atrophied under the influence of AMH, and testosterone and dihydrotestosterone have exerted a major influence on the normal development of internal and external genitalia, respectively. Torsion and infarction of improperly descended testes have been suggested.

Testicular regression syndrome. Vascularized fibrosis, hemosiderin deposition, and calcification are seen at the expected site of both gonads.

Intermediate in the spectrum of this disorder are patients with ambiguous genitalia and various combinations of wolffian and/or müllerian duct development. Testes that regress during the late embryonic period (days 43–59) usually secrete insufficient testosterone to affect the wolffian duct. The production of AMH is variable, resulting in poorly differentiated or rudimentary müllerian structures (incomplete inhibition). In the absence of systemic androgens, the external genitalia appear female.

Regression of the testes during the early fetal period (days 59–84), which is after Sertoli cell (AMH) and Leydig cell (testosterone) functions have begun or are about to begin, results in an individual with ambiguous external genitalia. Various combinations of wolffian and müllerian structures develop depending on the duration of androgen secretion and müllerian inhibition.

Regression of the testes during the mid-fetal period (days 84–120) results in more advanced masculinization of the external genitalia, although degrees of ambiguity are usually present. Since müllerian duct inhibition is normally completed by day 80, the müllerian structures will have been suppressed and wolffian structures develop.

Leydig Cell Deficiency

Leydig cell deficiency is a rare cause of male pseudohermaphroditism that may have more than one etiology. Some cases may lack Leydig cells altogether, while in others those present are dysfunctional, having an abnormal fibroblast-like morphology. Affected individuals have a 46,XY karyotype and testes with interstitial fibrosis, but lack mature Leydig cells and testosterone production. Tubules with Sertoli cells and, sometimes, immature spermatogonia are found. The müllerian structures are absent, indicating appropriate testicular production of AMH by Sertoli cells during fetal life. The wolffian duct system is developed either partially or fully such that identifiable vasa deferentia and epididymides are present. The phenotype varies and is usually female with unremarkable or ambiguous external genitalia, although unambiguous males with evidence of primary hypogonadism have been reported. The presence of wolffian duct development and the variable degrees of masculinized external genitalia indicate that some Leydig cells must have differentiated and functioned during early fetal life. Luteinizing hormone (LH) levels are elevated in affected individuals. Because this condition is so rare, it is uncertain whether the underlying defect is an absence or a defect of the LH–hCG receptor on the Leydig cell or with some other, unknown, factor arresting Leydig cell development.

Defects in Testosterone Synthesis

Congenital deficiency of any enzyme involved in testosterone production in the testis or adrenal gland results in a state of androgen deficiency (relative estrogen excess). The histologic appearance of the testicular tissue is variable. Although described occasionally as ‘normal,’ the photo­micrographs in some reports have disclosed large clusters of Leydig cells surrounding tubules lined only by Sertoli cells. Spermatogonia are often normal in children, but disappear by puberty. In general, the number of gonads studied for any of the conditions and the ranges of ages studied (infancy, childhood, adulthood) have been limited. Müllerian structures are absent, but wolffian duct structures may be present. The degree to which the external genitalia develop depends upon the type and severity of the defect.

Defect in Müllerian Inhibiting System (AMH and its Receptors)

The persistent müllerian duct syndrome, also known as ‘hernia uteri inguinalis,’ is a rare form of male pseudohermaphroditism where müllerian duct structures persist in 46,XY phenotypic males ( Figure 2.5 ). Most patients present when young with unilateral or bilateral cryptorchid testes, normal or almost normal male external genitalia, and an inguinal hernia into which prolapses an infantile uterus and fallopian tubes. Some patients may be older. The testes are histologically normal, wolffian duct structures are developed, the pubertal development is normal, and a rare patient has been fertile. Treatment is surgical, consisting of orchiopexy and herniorrhaphy with hysterectomy and bilateral salpingectomy.

Uterus in persistent müllerian duct syndrome.

If at operation any patient has a streak gonad or a tumor rather than bilateral testes, the diagnosis of mixed gonadal dysgenesis should be considered. In most cases of persistent müllerian duct syndrome, the vas deferens is embedded in the wall of the upper vagina and sometimes the müllerian structures must be left intact to preserve the vas deferens. Malignant testicular tumors have been reported in the very rare cases of adult patients with persistent müllerian duct syndrome and uncorrected cryptorchid testes.

Persistent müllerian duct syndrome is a heterogeneous group of disorders caused by at least two different defects in the müllerian inhibiting system. The most common is a defect in the anti-müllerian hormone gene, AMH (the protein is also called MIS). The next most common is a defective AMH type II receptor. The effect of these abnormalities is that some patients produce no biologically functional AMH, whereas others who produce normal amounts of biologically active AMH have end-organ insensitivity or an abnormality of the timing of AMH secretion. On rare occasion, a germ cell tumor may develop in the gonad, and, exceptionally, a müllerian-type tumor develops in the genital tract.

Androgen Receptor Disorders (Androgen Insensitivity Syndromes)

Disordered androgen receptor function results in various phenotypes, which range from phenotypic women with intra-abdominal testes, to individuals with ambiguous genitalia, and to phenotypic men with minimal clinical abnormalities. One classification scheme lists four categories, which are in order of increasing virilization (decreasing feminization):

• 1.
  

  Complete testicular feminization

  
  
• 2.
  

  Incomplete testicular feminization

  
  
• 3.
  

  Reifenstein phenotype: gynecomastia and hypospadias

  
  
• 4.
  

  Infertile and/or undervirilized man.

About 70% of cases share an X-linked recessive inheritance through the carrier mothers, the result of mutational defects in the androgen receptor gene, which is in the X chromosome’s long arm. In another 30%, the mutation arises de novo . Other genetic mutations are known, many of which are limited to individual families. These mutations may lead to functional absence of the androgen receptor because the primary sequences of the gene are affected. These patients generally present as complete testicular feminization. The more common defect results from single amino acid substitutions and is associated with the various other forms of the disease as described below. In rare patients the androgen receptor disorder occurs in combination with other unusual karyotypes, e.g., 47,XXY and 47,XYY.

Complete Androgen Receptor Insufficiency (Complete Testicular Feminization).

Complete testicular feminization, the most common form of male pseudohermaphroditism, occurs in 1 : 20,000 newborns. The external genitalia are phenotypically female ( Figure 2.6 ) and, for this reason, the condition is rarely diagnosed before puberty unless an inguinal hernia or labial mass is encountered or unless the disease is known to be familial. Primary amenorrhea is the most common complaint leading to evaluation and subsequent diagnosis. The medical history usually reveals that breast develop­ment occurred as expected at puberty, but remains in the pubertal state ( Figure 2.7 ). Pubic and axillary hair is scant ( Figure 2.8 ) and the vagina is shortened. The epididymides are usually cystic and not connected to the testes. The vasa differentia, seminal vesicles, and prostate are absent. As a rule, both the cervix and the uterine corpus are absent. Fallopian tube fragments are found in one-third of cases. The testes are cryptorchid and may be located in the inguinal canal, the pelvis, or rarely the labia.

‘Normal’ phenotypic feminine genitalia in androgen insensitivity syndrome.

Immature breast development and lack of axillary hair in androgen insensitivity syndrome.

Lack of pubic hair in androgen insensitivity syndrome.

In the complete or almost complete form of the syndrome, the individual exhibits a female gender identity with normal extragenital erotogenic sensitivity and normal maternal attitude, emphasizing the need to support the patient as a woman, even with reconstructive surgery. This condition should be differentiated from defects in steroidogenic factor-1 mutations (XY, sex reversal with androgen insensitivity-like features) with which it can be confused.

The gonads in infants and young children are relatively normal but, by age 5 years, they show abnormalities. By young adulthood, the gonad is often involved with benign or malignant tumors as described later. If tumors are not present by this age, the gonad is usually small and on section is tan to brown and traversed by thin white bands ( Figure 2.9 ). Microscopic examination of the testicular parenchyma discloses immature seminiferous tubules. At earlier ages, the tubules may be clustered in small aggregates ( Figure 2.10 ), but with time they become more sparsely distributed ( Figure 2.11 ). Spermatogonia may be present, but spermatogenesis is absent. The number of spermatogonia found is also age dependent, diminishing as the patient ages. The interstitium, which resembles ovarian stroma, is usually abundant at an early age and over time often becomes more fibrous ( Figure 2.12 ). Fetal-type Leydig cells may be abundant. The Leydig cells in individuals with testicular feminization have an ultrastructure typical of cells involved in active hormone synthesis and the systemic androgen levels in these individuals are typically elevated. These findings indicate that the pathologic defect in the testicular feminization syndrome is an end-organ defect and not lack of hormone production by the testes.

Testis in androgen insensitivity syndrome without tumor.

Androgen insensitivity syndrome. Immature seminiferous tubules, numerous Leydig cells, and rare foci of immature ovarian-type stroma constitute the testis.

Androgen insensitivity syndrome. Scattered immature seminiferous tubules are embedded in the dense ovarian-type cortical stroma present in the testis.

Androgen insensitivity syndrome, gonad in an older patient. Dense ovarian-type cortical stroma with extremely rare scattered immature seminiferous tubules constitute the testis.

Most testes of affected individuals contain multiple benign nodules that are discrete, firm, yellow to brown, and bulge above the sectioned surface ( Figure 2.13 ). These can be hamartomatous (e.g., Sertoli cell adenoma) or neoplastic (e.g., dysgerminoma or gonadoblastoma like). One finding we have seen characteristically is a 1–2 cm firm white nodule of hyalinized smooth muscle leiomyoma-like tissue that is usually present at one pole of the testis ( Figure 2.14 ). Reactivity for smooth muscle actin confirms its smooth muscle origin ( Figure 2.15 ). Additionally, hamartomatous nodules are present, usually bilaterally, in virtually every case. The typical size varies from 1 mm to 1 cm, but occasionally up to 4 cm. The bulk of the nodule consists of seminiferous tubules lacking lumina ( Figure 2.16 ). Spermatogonia may be present ( Figure 2.17 ). The seminiferous tubules located outside the nodules have a lamina propria that is of normal thickness in prepubertal testes, but thickened and hyalinized in the adult. Sertoli cell adenomas, which average 3 cm in diameter, but range to 25 cm ( Figure 2.18 ), are hamartomas composed predominantly or exclusively of closely packed immature seminiferous tubules lacking lumina and lined by immature, uniform Sertoli cells ( Figure 2.19 ), some with germ cells ( Figure 2.20 ). The interstitium in the testes of affected patients often resembles ovarian stroma, and frequently contains Leydig cells ( Figure 2.10 ). On rare occasion, Leydig cell nodules form, and have been considered benign tumors ( Figure 2.21 ). Even though tumors have been reported occasionally as malignant, none has shown evidence of invasion or dissemination grossly or microscopically. In summary, the name applied to each type of nodule is somewhat arbitrary and depends largely upon the types of component present as well as their number and size. Most nodules are classified as hamartomas, Sertoli cell adenomas, or rarely as Leydig cell tumors.

Androgen insensitivity syndrome. Several small yellowish Sertoli cell adenomas are present throughout the specimen. The large white mass at the inferior pole may represent a hypertrophied gubernaculum testis or a leiomyoma present since birth.

Nodule of hypertrophied gubernaculum in androgen insensitivity syndrome.

(A) Androgen insensitivity syndrome with Sertoli adenoma (right) and hypertrophied gubernaculum (left). The adenoma expresses AMH (B) , and smooth muscle actin is positive in the gubernaculum (C) .

Sertoli cell adenoma in androgen insensitivity syndrome. The tubules lack lumens.

Seminiferous tubules with occasional spermatogonia in androgen insensitivity syndrome.

Giant Sertoli cell adenoma.

Interface of Sertoli cell adenoma (right) and adjacent degenerative seminiferous tubules (left) in androgen insensitivity syndrome.

Germ cells in Sertoli cell adenoma.

Leydig cell tumor in androgen insensitivity syndrome. Detail of a well-circumscribed gross nodule showing sheets of cells with large central nucleus and copious cytoplasm.

Malignant gonadal tumors develop with increasing frequency with age in patients with testicular feminization. Seminoma is the most commonly encountered gonadal malignancy in this syndrome. Intratubular germ cell neoplasia is sometimes seen, either independently or in association with seminoma ( Figures 2.22 and 2.23 ). Other malignant germ cell tumors and malignant sex cord tumors are also encountered rarely. Unlike mixed gonadal dysgenesis in which tumors develop in young individuals, the risk of malignancy in patients with testicular feminization is only 4% by the age of 25 years, but reaches 33% by 50 years. Since malignant tumors rarely develop before completion of puberty, castration can usually be delayed until after adolescence, thus permitting the patient to undergo normal pubertal development with spontaneous female secondary sex characteristics.

Seminoma in androgen insensitivity syndrome.

Seminoma in androgen insensitivity syndrome. Detail of neoplastic germ cells surrounded by fibrous stroma invested with numerous lymphocytes.

Partial Androgen Receptor Insufficiency (Incomplete Testicular Feminization).

About 10–50% of patients with the androgen insensitivity syndrome have an incomplete variant. The clinical manifestations vary depending on the classification system used. If restricted, it resembles complete testicular feminization except that there is partial fusion of the labioscrotal folds and usually some clitoromegaly at birth. If inclusive of all forms of the androgen insensitivity syndrome that are not considered complete testicular feminization, then greater percentages of patients will look and be raised as males. Viewed broadly, patients with partial androgen receptor insufficiency form one of the largest groups of intersex patients born with male sex ambiguity. Like the complete form, underdeveloped wolffian duct derivatives are often present. If the diagnosis is established during childhood, gonadectomy should be performed before puberty, since disfiguring virilization may accompany breast development at puberty. Estrogen therapy should be given at the appropriate time to initiate feminization. The pathologic findings are those described for the complete form of testicular feminization.

Other Forms.

Reifenstein syndrome, infertile male syndrome, and undervirilized male syndrome are other forms of incomplete androgen insensitivity in which the phenotype is male. There are few reports describing the microscopic findings of the gonads.

• •
  

  Patients with Reifenstein syndrome usually present with gynecomastia and severe hypospadias, like children or teenagers with perineoscrotal hypospadias. However, the phenotypic spectrum is wide, even within the same affected family with a single androgen receptor abnormality in all affected family members. Additional abnormalities include female habitus, azoospermia, cryptorchism, and hypoplasia or absence of wolffian duct structures.

  
  
• •
  

  Infertile male syndrome is a rare androgen receptor defect characterized by a phenotypically normal man with infertility caused by azoospermia.

  
  
• •
  

  In the undervirilized male syndrome, the individual is a male with gynecomastia, a small penis, decreased beard and body hair, a normal male urethra, a normal sperm density, and an identifiable androgen receptor defect. Most affected individuals are infertile.

5α-Reductase Type 2 Deficiency

This is a disorder of testosterone metabolism. Functional deficiency from the mutated enzyme, 5α-reductase 2, impairs the conversion of testosterone to dihydrotestosterone, the hormone that masculinizes the indifferent urogenital sinus and induces development of the prostate. The disorder, formerly known as ‘pseudovaginal perineoscrotal hypospadias,’ has an autosomal recessive inheritance and is rare. Most reported cases come from family clusters found in a number of relatively isolated geographic locations. Several unrelated patients have had an identical mutation, suggesting a common ancestral founder. The type 2 isoenzyme develops in the fetus and is detectable in the genital skin and the male accessory sex organs. The type 1 isoenzyme is not detectable in the fetus; its activation in skin at the time of puberty is responsible for the clinical virilization these patients later express.

Affected males are usually phenotypically female with female to ambiguous external genitalia at birth. The small clitoris-like phallus lacks a urethral orifice. In most affected individuals the urogenital sinus opens on the perineum and within the sinus an anterior orifice leads to the urethra and a posterior orifice to a blind vaginal pouch. The testes are in the inguinal canals or labia. The müllerian-derived structures are absent whereas wolffian-derived structures (vas deferens, epididymis, and seminal vesicle), the anlagen of which respond to testosterone, are normal.

At puberty, virilization occurs due to type 1 isoenzyme activation, but the breasts fail to develop. The penis lengthens, the bifid scrotum grows and becomes rugated and hyperpigmented, and the testes enlarge and descend. Testicular biopsy specimens reveal spermatogenesis and tubular atrophy in some individuals, complete spermatogenic arrest and Leydig cell hyperplasia in others. The prostate remains rudimentary and the seminal vesicles underdeveloped, which results in affected adults having highly viscous semen and extremely low ejaculate volume. Erection and ejaculation are possible in some affected individuals, but few individuals are fertile.

Neonates with this disorder frequently go unrecognized and are raised as females. After the virilization that accompanies puberty, individuals raised as girls sometimes reverse their sex roles and function as men, often with a stormy period of adjustment. Individuals with a male gender identity benefit from surgical correction of hypospadias and cryptorchism. High doses of testosterone enhance virilization. Persons raised as females who elect to continue to function as females into adulthood benefit from orchiectomy before the onset of puberty to avoid the accompanying virilization. Estrogen therapy is useful to promote feminization. No patients are known to have developed testicular germ cell tumors.

Defect in Cholesterol Synthesis (Smith–Lemli–Opitz Syndrome).

Cholesterol synthesis is required for testosterone and all other hormones that the gonads and adrenal glands produce. The Smith–Lemli–Opitz syndrome, inherited as an autosomal recessive trait, results from an enzymatic defect in the last step of cholesterol metabolism (reduction of 7-dehydrocholesterol due to mutations in the DHCR7 gene). These patients variably show ambiguous genitalia with hypo­spadias, and more constantly a wide range of other somatic abnormalities including a distinctive facial appearance (microcephaly, ptosis, small upturned nose, micrognathia), cleft palate, and limb anomalies (proximally placed thumbs, polydactyly, and 2–3 toe syndactyly). Several 46,XY infants with female external genitalia and intra-abdominal testes with epididymides and deferent ducts had a normally shaped uterus and vagina. The Y chromosome is normal in these cases, with the affected DHCR7 gene located at 11q13.

Congenital Lipoid Adrenal Hyperplasia.

Congenital lipoid adrenal hyperplasia (lipoid CAH), the most severe form of CAH, results from mutations in the steroidogenic acute regulatory ( STAR ) gene as the primary defect ( Table 2.2 ). The STAR gene, located on chromosome 8, encodes a protein that helps transport cholesterol into the mitochondria. The principal effect is the absence of cholesterol intermediates capable of converting to pregnenolone. Additional damage occurs from the subsequent steroidogenic loss independent of STAR , and results from the effects of the cholesterol esters that accumulate in the adrenal cortex. This leads to cellular damage in the form of salt wasting, hyponatremia, hypovolemia, hyperkalemia, acidosis, and death in infancy. This state of hypergonadotropic hypogonadism shows markedly elevated levels of gonadotropic hormones (LH, follicle-stimulating hormone, ACTH), but markedly impaired synthesis of all gonadal and adrenal cortical steroids, even with trophic stimulation tests.

In the 46,XY male, the external genitalia may be ambiguous to female, but sufficient testosterone must have been secreted during embryogenesis since the internal genitalia are male. Some of these patients may have a palpable gonad in the inguinal canal. These testes disclose immature seminiferous tubules with spermatogonia. Occasional Leydig cells are present. The germ cells may disappear over time, resulting in a Sertoli-only syndrome, although this is not inevitable. Germ cells can persist and rarely develop into intratubular germ cell neoplasia.

CAH.

Several inherited enzymatic defects, which cause the syndrome of CAH, involve both the synthesis of adrenal mineralocorticoid and glucocorticoid hormones as well as the adrenal and testicular sex hormones. Because of these genetic defects, one or more adrenal cortical enzymes fail to be synthesized or are defective.

The deficiency of 3β-hydroxylase dehydrogenase, like the 20,22-desmolase deficiency, results in decreased synthesis of mineralocorticoid and glucocorticoid hormones as well as adrenal and testicular sex hormones, and may lead to life-threatening salt wasting in infancy. DHEA, a weak androgen secreted in high amounts, results in slight clitoral enlargement in the female, but rarely completely masculinizes the external genitalia in males. Hence, the male may be born with ambiguous genitalia and may resemble a virilized female. Males in whom the defect is partial may be born with hypospadias, but at puberty develop gynecomastia. Over time, the Sertoli cells, which may initially appear normal, undergo atrophy and the spermatogonia change from abundant to rare to absent. The number of Leydig cells may increase with age, but it is unclear whether the hyperplasia is absolute or relative to the atrophy of other elements.

In contrast to the early age of diagnosis in the above two syndromes, the diagnosis in most patients with 17β-hydroxylase deficiency is not suspected until the anticipated time of puberty or later. Occasionally, detailed steroid analysis of the urine of a newborn male presenting with ambiguous genitalia has been performed, indicating that the correct diagnosis can be made in the young.

Deficiency of two enzymes, 17,20-desmolase and 17-hydroxysteroid dehydrogenase (formerly 17-ketosteroid reductase), results in deficient testosterone synthesis but does not affect the production of either mineralocorticoids or glucocorticoids. The former defect (conversion of 17-hydroxypregnenolone to DHEA) is extremely rare. The patients present with ambiguous external genitalia and inguinal or intra-abdominal testes. Spermatogonia were present in the testes of infants but were absent in the biopsies of their older teenage relatives. All had third-degree hypospadias, but normal male internal ductal differentiation.

Genetic males with 17β-hydroxysteroid dehydrogenase (17β-HSD) deficiency have uniformly been raised as females and have unambiguous female external genitalia. Most are diagnosed at or after puberty when they fail to menstruate and instead show signs of virilization such as clitoromegaly (enlarged phallus) and hirsutism. Breast development may or may not take place. At surgery, müllerian duct derivatives are absent, consistent with normal AMH action. Wolffian duct differentiation, indicative of testosterone secretion during embryogenesis, is normal. The testes present in the inguinal canal or labia majora contain rare to no spermatogonia, and may exhibit numerous Leydig cells. Detailed endocrine studies have shown that testicular 17β-HSD is under a different genetic control from that in extragonadal tissues, and while affected males lack testicular 17β-HSD, the extragonadal activity is normal or enhanced. More than 15 mutations have been identified in the responsible gene.