Clinical case
A 58-year-old G2P2 female presents with a 10 cm complex adnexal mass and postmenopausal bleeding. CT imaging also demonstrates a 4 cm perihepatic tumor implant ( Fig. 2.1 ). Image-guided biopsy of this implant demonstrates an adult granulosa cell tumor (AGCT), and preoperative inhibin A was elevated at 22 pg/mL and inhibin B was elevated at 751 pg/mL. How do you treat this patient?
Epidemiology
Incidence/mortality
The sex cords and stromal compartments collectively comprise the mesenchymal support structures and sites of local and systemic hormone production for both the male and female gonad. Pure sex cord tumors include those arising from granulosa cells and Sertoli cells, as well as the rarer entity sex cord tumor with annular tubules which occur in the setting of Peutz–Jeghers syndrome (PJS) in up to 30% of cases. Pure stromal malignancies of the ovary are generally rare and include fibrosarcomas and malignant steroid cell tumors. Mixed Sertoli–Leydig cell tumors (SLCTs) are uncommon, and although they may be associated with androgenic excess, the majority of such tumors described in large historical series exhibited benign behavior. The World Health Organization classification of sex cord/stromal tumor is shown in Table 2.1 . The incidence rate of sex cord/stromal ovarian cancers in the United States has been estimated to be approximately 0.5 per 100,000 using large cancer registries, but this may be an underestimate due to misclassification of early stage disease as nonmalignant. For example, the category “Granulosa cell tumor, adult type” carries a nonmalignant behavior code in the International Classification of Diseases for Oncology (ICD-O) and thus is excluded from many cancer registry analyses. In support of this observation are longitudinal multinational population data from Scandinavia showing that between the years 1953 and 2012, the incidence rate of ovarian granulosa cell tumors alone was between 0.6 and 0.8 per 100,000, a higher rate than has been reported for all sex cord/stromal ovarian cancers in the United States.
| Sex cord/stromal tumors |
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| Pure stromal tumors |
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| Pure sex cord tumors |
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| Mixed sex cord/stromal tumors |
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The median age for diagnosis of AGCT of the ovary is around 45–50 years with most diagnoses occurring in the fourth of fifth decade of life. The juvenile-type of granulosa cell tumor (JGCT) of the ovary is histologically distinct from AGCT of the ovary and arises most often during the prepubertal years. Including both benign and malignant entities, SLCTs tend to arise in the third decade of life but there is wide variance in the reported age of onset. A review of patients in the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database showed women diagnosed with SLCTs were younger than those diagnosed with granulosa cell tumors (median age 32 vs 51). Staging of sex cord/stromal tumors of the ovary uses the same FIGO system employed in the management of more common epithelial malignancies of the ovary. In general, sex cord/stromal tumors are more likely to be stage I at the time of diagnosis (75%–90%) than are the more common epithelial subtype of ovarian cancers. Largely due to the combination of a favorable stage distribution at diagnosis and indolent behavior, 10-year survival rates for SLCT and AGCT of the ovary are generally excellent for completely resected disease. Stage at diagnosis is the clinical factor that has most consistently been linked to recurrence risk and outcomes across sex cord/stromal tumor subtypes. Additionally, poorly differentiated SLCTs or those with heterologous elements are more likely to recur and exhibit malignant behavior following initial surgical resection. Some evidence also suggests that the presence of a retiform pattern may also portend a higher risk of SLCT recurrence. Among AGCT of the ovary, several factors including mitotic rate, cellular atypia, and tumor size, patient body mass index at the time of diagnosis have been variably associated with recurrence risk and survival outcomes.
Etiology/risk factors
There are no known environmental risk factors for the development of sex cord/stromal tumors. For example, a population-based cohort study in Scandinavia examined the risk of granulosa cell tumor across time and occupation between the years 1953 and 2012. The stability of granulosa cell tumor incidence over the observation period of this study suggests that the usage of hormonal contraceptives, postmenopausal hormone replacement therapy, or fertility treatments do not substantially influence patterns of risk for this disease, since the use of these interventions changed dramatically throughout the 60-year observation period of this study. In the United States, both Sertoli–Leydig and granulosa cell tumors occur more frequently in Black women compared to White women or Asian/Pacific Islanders.
Genetic evidence indicates that germline mutations may account for a subset of sex cord/stromal tumors. Hotspot somatic missense mutations in the RNase IIIb domain of the gene coding for the microRNA processing enzyme DICER1 are found in approximately 60% of SLCTs, with a smaller subset of affected individuals also carrying truncating germline DICER1 mutations. Evidence from public exome sequencing datasets indicate that at least 1 in 10,000 individuals likely carry such a germline DICER1 mutation, representing a Mendelian syndrome associated with an increased risk of SLCT as well as a spectrum of other malignancies including pediatric pleuropulmonary blastoma. The association between sex cord tumor with annular tubules and PJS was known from the time this tumor type was first described in 1970. Germline pathogenic mutations in the STK11 gene, the causative lesion of PJS, account for approximately one-third of all cases of sex cord tumor with annular tubules. In contrast, STK11 mutations are rare in sporadic sex cord tumor with annular tubules.
Pathology
Adult granulosa cell tumor
Gross
The majority of AGCT are unilateral. The tumor size can vary from microscopic to extremely large (mean 10.0 cm). The tumors can be either entirely solid, solid and cystic or less commonly entirely cystic. The cyst contents may be serous or more typically hemorrhagic and rupture may result in hemoperitoneum. The cut surface of the solid component is usually yellow white in appearance.
Microscopic features
AGCT can demonstrate a variety of patterns including diffuse, microfollicular, macrofollicular, insular (discrete nests), trabecular/corded, gyriform, pseudopapillary, and watered-silk. The diffuse pattern is most common and is composed of fascicles of spindle cells ( Fig. 2.2 ). The Call-Exner body ( Fig. 2.3 ) characterized by the presence of tumor cells around a central space containing eosinophilic secretions, degenerating nuclei or hyaline material, resulting in the microfollicular pattern is the histologic hallmark of these tumors. The background stroma can be either fibromatous or thecomatous and in some cases can largely overrun the granulosa cell component, making it difficult to recognize ( Fig. 2.4 ). The nuclei of AGCT are oval and monotonous with fine chromatin and indistinct nucleoli. The coffee bean appearance secondary to the presence of nuclear grooves ( Fig. 2.5 ) is characteristic. Mitotic activity is variable but is low in most cases (< 4/10 hpfs). Of the various pathologic parameters no single one is predictive of adverse outcome for stage IA patients. Pathologic parameters such as tumor size, nuclear atypia, and the predominant histologic pattern of the tumor have not been shown to consistently predict behavior in patients with Stage 1A disease. There is some controversy about the mitotic index in that some authors report worse outcome with mitoses anywhere from > 4 to > 10/10 hpfs, while others have not found mitotic index to be predictive of behavior.
Ancillary testing
AGCT and all other sex cord tumors described in this chapter are usually positive for SF-1, inhibin ( Fig. 2.6 ), and calretinin. Reticulin stain usually highlights loss of reticulin fibers around individual tumor cells.
Differential diagnosis
Due to the numerous histologic patterns of AGCT the differential diagnosis is quite vast and depends on the dominant pattern. Diffuse AGCT can be misinterpreted as cellular fibroma or endometrial stromal sarcoma. Loss of reticulin fibers around individual tumor cells in AGCT can help distinguish it from cellular fibroma. Endometrial stromal sarcomas have short spindle cells with typical spiral arteriole-like vascular pattern, lack of nuclear grooves and CD10 positivity, while they are negative for inhibin, calretinin and SF-1.
Endometrioid adenocarcinoma, particularly when they have sex cord-like pattern, can closely mimic the microfollicular pattern of AGCT. Areas of conventional pattern of endometrioid carcinoma with squamous and or mucinous differentiation are usually present and should facilitate this diagnosis. Furthermore, an adenofibromatous component and endometriosis will further support this diagnosis. Endometrioid carcinomas are positive for EMA and PAX-8 while negative for inhibin/calretinin/SF-1.
The nested appearance of the insular pattern of AGCT can resemble carcinoid tumor. The latter tumor has salt and pepper chromatin, lacks nuclear grooves and is positive for neuroendocrine markers synaptophysin and chromogranin. Markers of sex cord differentiation such as SF-1, inhibin and calretinin are negative. FOXL2 immunostain is positive in majority of sex cord/stromal tumors and can be used as an additional marker to distinguish sex cord/stromal tumors from epithelial tumors and other mimics, though this stain is not routinely available in most laboratories.
Lastly, the macrofollicular pattern of AGCT can mimic a follicular cyst. If the cyst is larger than 10 cm, has loss of theca cells and shows nuclear grooving and organization of tumor cells, a diagnosis of AGCT would be favored.
Molecular alterations
FOXL2 belongs to the family of forkhead/winged-helix transcription factors and has been shown to play an important role in the formation of follicles in the adult ovary. The majority of AGCT harbor a missense mutation c.402C-G (p.C134W) in the Forkhead box L2 ( FOXL2) gene. This mutation is absent in most sex cord tumors as well as epithelial tumors and is fairly sensitive and specific for AGCT. Rarely thecomas and JGCT have been reported to have the FOXL2 mutation. Molecular testing for FOXL2 is not typically performed in routine practice but may be helpful in challenging cases such as fibromatous AGCT.
Juvenile granulosa cell tumor
Gross
JGCT are typically unilateral and present with disease confined to the ovary. These tumors can range from small to very large (mean, 12 cm). Similar to AGCT, the cut surface of the tumor can be purely solid, solid and cystic, or only cystic.
Microscopic findings
Histologically JGCT are composed of granulosa cells that can either have a diffuse or nodular pattern. Necrosis and hemorrhage may be present. Follicle-like spaces filled with basophilic or eosinophilic material are a key histologic feature in the diagnosis of JGCT ( Fig. 2.7 ). A subset of cases may have a pseudopapillary pattern. The tumor cells often have abundant pale pink or clear cytoplasm and the nuclei are small, round or oval. Nuclear grooves are rare or absent. Tumors with brisk mitotic activity and bizarre atypia ( Fig. 2.7 ) are seen in about 10% of cases, but these findings do not appear to have an impact on prognosis. Small foci of JGCT can sometimes be admixed with AGCT or Sertoli cell tumors and these cases are classified based on the dominant histotype.
Ancillary testing
JGCT are positive for the usual sex cord markers such as inhibin, calretinin, CD56 and SF-1. A small subset may be positive for FOXL2 immunostain but its use in routine diagnosis is limited.
Differential diagnosis
Differentiating JGCT from AGCT can be difficult particularly when the latter tumor shows prominent luteinization. Young age at presentation, nodular pattern, follicle-like spaces, and lack of nuclear grooves would favor JGCT.
Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) can closely mimic JGCT as both tumors are characterized by the presence of follicle-like spaces. SCCOHT is composed of small cells with minimal cytoplasm as well as rhabdoid morphology (large cell variant), and are negative for sex cord markers. Clinically, unlike JGCT, SCCOHT presents with advanced stage disease and a subset of patients have accompanying hypercalcemia. Recently studies have shown that most SCCOHT have either somatic or germline mutations in the SMARCA4 gene, and lack SMARCA4 (BRG1) expression by immunohistochemistry. This latter finding is virtually diagnostic of SCCOHT and facilitates the correct diagnosis.
Molecular alterations
The molecular mechanisms of JGCT are not that well studied. Trisomy12 is the most frequent cytogenetic abnormality identified and is present in most cases tested so far. FOXL2 mutations rarely occur in JGCT. Recent studies have shown that JCGT have activating alterations in AKT1 and GNAS that may contribute to the pathogenesis of these tumors.
Sertoli–Leydig cell tumor
Gross
SLCT range from 2 to 35 cm in size. The cut surface is usually yellow-white and solid but can also be solid and cystic or rarely entirely cystic. Hemorrhage and necrosis and may be present.
Microscopic findings
Histologically, the tumors are broadly categorized as well, intermediate, or poorly differentiated based on the proportion of tubular and spindle component present. The tubular component is less represented in intermediate and poorly differentiated tumors. Tumors typically are composed of varying amounts of Sertoli cells and Leydig cells ( Fig. 2.8 ), and the latter may be hard to identify in poorly differentiated tumors. Well-differentiated SLCTs are composed of closely packed hollow or solid tubules separated by fibrous stroma within which clusters of Leydig cells are present. The nuclei of the tubules in well differentiated SLCTs show minimal to no atypia or mitotic activity. Leydig cells are characterized by abundant pink cytoplasm and single small nucleus. Neither heterologous elements nor retiform pattern are identified in well differentiated SLCTs.
SLCTs of intermediate differentiation have a characteristic low power appearance of alternating hyper and hypocellular areas. The cellular areas are composed of short spindle cells with minimal cytoplasm. Admixed Sertoli tubules as well as cords and trabeculae may be present. The Leydig cells may be present either within spindle cell areas or at the periphery of the cellular nodules. The Leydig cells have bland nuclei, no mitotic activity and may rarely contain Reinke crystals.
Poorly differentiated SLCTs can be challenging to diagnose as they resemble a high-grade sarcoma, NOS. Typical aforementioned features of SLCT may not be readily identified and additional sampling of the tumor is usually necessary to facilitate the correct diagnosis.
Retiform SLCTs present in younger age group (average 15 years) and patients are less likely to be virilized. The retiform pattern is only associated with intermediate and poorly differentiated SLCTs. Histologically, the tumor cells are arranged in anastomosing, branched/slit-like spaces reminiscent of the normal rete testis.
Heterologous elements are present in approximately 20% of intermediate or poorly differentiated SLCTs. They may be epithelial or mesenchymal. The epithelial-type heterologous elements is more common and composed of glands lined by mucinous epithelium which may be benign, borderline, or carcinoma. Carcinoid tumors have also been described as a heterologous element in SLCTs. The most common mesenchymal-type heterologous elements are immature skeletal muscle (rhabdomyosarcoma) and immature fetal-type cartilage.
Ancillary testing
Immunohistochemical staining of SLCTs is similar to other sex cord/stromal tumors and they are variably positive for inhibin, calretinin and SF-1.
Differential diagnosis
The differential diagnosis of SLCTs is dependent of the degree of differentiation of these tumors. For well-differentiated SLCTs, the two most important differentials to include are sertoliform endometrioid adenocarcinoma and carcinoid tumors.
Diffuse-type AGCT with a prominent corded and trabecular pattern with admixed luteinized stromal cells can mimic SLCTs of intermediate differentiation. Female adnexal tumor of probable Wolffian origin can have some overlapping features with SLCTs but the they lack sertoliform tubules and Leydig cells, and patients do not present with androgenic symptoms.
Molecular alterations
SLCTs are now ascribed to be part of DICER1 syndrome, also known as the pleuropulmonary blastoma familial tumor and dysplasia syndrome, as germline DICER1 mutations have been identified in these patients. SLCTs with DICER-1 mutations typically occur in younger women and are either of intermediate or poor differentiation, and have retiform pattern or heterologous elements. On the other hand FOXL2 mutated SLCTs occur predominantly in postmenopausal women also with intermediate/poor differentiation, but lack retiform and heterologous elements.
Sex cord tumor with annular tubules
Gross
In sporadic cases of sex cord tumors with annular tubules (SCTAT), the tumor size is variable and can range from microscopic to large (up to 20.0 cm). However, in patients with PJS, the tumors are bilateral, small, calcified and usually incidentally detected. The tumors are usually solid but can also have a cystic component and have a yellow white cut surface.
Microscopic findings
The characteristic histologic appearance is the presence of “annular tubules” either simple or complex that encircle the central hyaline basement membrane like material ( Fig. 2.9 ). In the complex type, large islands composed of a network of communicating tubules is present. There is no nuclear atypia and mitoses are usually rare.
Ancillary testing
SCTAT are positive for SF-1, inhibin and calretinin similar to other sex cord/stromal tumors.
Differential diagnosis
The differential diagnosis for SCTAT includes AGCT, Sertoli cell tumor and gonadoblastoma. In AGCT, Call-Exner bodies may mimic the annular tubules of SCTAT, however, the central hyalinized basement membrane material and the ring-shaped tubular pattern seen in the latter are not present in AGCT. Sertoli cell tumor are characterized by individual tubules which is not seen in SCTAT, and they lack the typical annular tubules. Gonadoblastoma can mimic SCTAT due to similar nested pattern, areas of hyalinization and presence of calcification. However, these tumors have both germ cells and sex cord tumor cells and the former are not seen in SCTAT. The germ cells are larger in size and can be highlighted by stains such as OCT4. Furthermore, gonadoblastoma occurs almost exclusively in patients with gonadal dysgenesis.
Molecular alterations
There are only few reports on the molecular genetic alterations of SCTAT. In one study, germline mutations in the STK11 gene and loss of heterozygosity in the 19p13.3 region were found in the two tested PJS-associated SCTATs. Somatic mutations in the coding region of STK11 were not identified in the 5 tested sporadic SCTATs.
Diagnosis and workup
Signs and symptoms
The majority of sex cord/stromal tumors are diagnosed in symptomatic patients, and depending on size these symptoms can include distension or abdominal pain referable to mass effect from the tumor itself. Case reports describe women with advanced or recurrent granulosa cell tumors presenting with acute abdominal pain secondary to hemoperitoneum, but this is a rare occurrence in modern practice. Estrogen excess is frequently associated with AGCT of the ovary but can also be seen in other sex cord/stromal tumor subtypes. When present, estrogen production by the tumor can result in abnormal uterine bleeding or other menstrual abnormalities that lead an affected woman to seek medical evaluation, leading to the diagnosis of sex cord/stromal tumor. Similarly, SLCT and pure Leydig cell tumors can produce excess testosterone in 30%–50% of cases, which is often sufficient to enjoin a diagnostic work up as a result of amenorrhea, hirsutism, or frank virilization. A significant minority of sex cord/stromal tumor are never symptomatic and instead are diagnosed incidentally during routine physical examination or imaging studies performed for unrelated indications. It is rare for sex cord/stromal tumor to present with metastatic disease.
Physical exam findings
Pelvic examination reveals a palpable adnexal mass in most cases of sex cord/stromal tumor, which is often firm in character and most often unilateral. In a minority of cases, physical findings associated with hormonal excess are present. In the case of androgen excess, as with SLCT or Leydig cell tumors, the physical findings can range from mild hirsutism to frank virilization including clitoromegaly, deepening of the voice, or other changes in body morphology. As described above, estrogen excess can lead to abnormal uterine bleeding, infertility, or other symptoms that prompt an evaluation eventually leading to the diagnosis of sex cord/stromal tumor.
Differential diagnosis
The preoperative differential diagnosis is often broad in cases where an adnexal mass is ultimately proven to be a sex cord/stromal tumor. In many cases, there is no radiographic evidence of extraovarian spread. Even when the presence of solid elements on pelvic ultrasound suggests a sex cord/stromal tumor, many of these neoplasms will be benign fibromas or thecomas that can be definitively addressed with removal of the affected ovary. In the premenopausal age group often affected by many types of sex cord/stromal tumor, the differential diagnosis of a complex adnexal mass must include malignant germ cell tumors of the ovary and appropriate serum tumor markers [human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), lactate dehydrogenase (LDH)] can be obtained preoperatively as indicated. The recommended approach to the initial evaluation of a suspected sex cord/stromal tumor is shown in Table 2.2 .
