Chapter 36 Benign tumours, cysts and malformations of the genital tract
MALFORMATIONS OF THE GENITAL TRACT
In a female fetus the Müllerian ducts develop from the paramesonephric ducts, growing caudally on each side. By the 35th day after fertilization the lower part of the ducts change direction and grow towards the midline, where they meet and fuse with each other and then grow caudally once again. By the 65th day they have completed the fusion and their medial walls have gradually disappeared to form a single hollow tube (Fig. 36.1). The most caudal portion, which will become the vagina, becomes solid and fuses with an ingrowth of endodermal cells from the cloaca. By the 20th gestational week, the solid growth has recanalized and the external genitalia have formed (Fig. 36.2).
Fig. 36.1 Development of the genital organs, from the Müllerian duct in the female and the Wolffian duct in the male.
Malformations of the genital tract occur when the process described above does not occur. The error may be one of failure of the recanalization process, or may be a failure of the two Müllerian ducts to fuse.
Failure of recanalization
The most common defect is an imperforate hymen or transverse septum, which should be detectable during the examination of the neonate. If it is not detected until after puberty, menstrual discharge may collect in the vagina and, in long-term cases, may distend the uterus and tubes (Fig. 36.3). Treatment is to make a cruciate incision in the hymen septum and permit the inspissated fluid to escape slowly. Less common defects produce complete or partial vaginal atresia.
Failure of the ducts to form or to fuse
One or other duct may fail to form, and only one Fallopian tube and a distorted unicornate uterus may be found. If both ducts fail to form the woman will be amenorrhoeic.
Failure of the two Müllerian ducts to fuse leads to one of several malformations (Fig. 36.4). Most of these malformations do not reduce the woman’s fertility, but should pregnancy occur there is an increased risk of late miscarriage and premature labour. A subseptate uterus may lead to recurrent abortion, and can be treated by excising the septum by surgery or laser. If the woman has a bicornuate uterus and becomes pregnant, the fetus may present as a transverse lie in late pregnancy.
VULVAL TUMOURS
Because the tissues of the vulva are covered by skin, tumours arising in them are similar to those occurring in any part of the integument. A few women develop vulval varicosities, which may cause discomfort and are more marked in pregnancy.
VAGINAL TUMOURS
Vaginal cysts are uncommon, but occasionally one develops in the lateral wall of the upper vagina. It is a cyst of a remnant of the degenerate Wolffian duct and is referred to as a Gartner’s duct cyst. A cystic swelling may occur in the anterior wall of the vagina, directly below the urethra: this is a urethral diverticulum. If it becomes infected, the woman complains of dysuria and frequency of urination. Occasionally, a myoma may develop beneath the vaginal epithelium.
CERVICAL TUMOURS
The most common cervical tumour is a cervical polyp, which occurs as the result of localized hyperplasia of the epithelium and stroma covering a ridge between two clefts in the cervical canal. The columnar epithelium covering the polyp may undergo squamous metaplasia, or ulcerate. The main symptoms are intermittent or postcoital bleeding, although many cervical polyps are symptomless. The diagnosis is made on inspection of the cervix. The polyp can be removed by twisting the pedicle, and the tissue should be sent for histopathology. Other tumours that may be detected occasionally are genital papillomata and fibroids.
UTERINE TUMOURS
Endometrial polyps
Endometrial polyps may occur in association with endometrial hyperplasia and may be a cause of abnormal uterine bleeding. They are detected by curettage, provided a polyp forceps is also introduced into the uterus (Fig. 36.5), or by hysteroscopy.
Uterine fibroids (leiomyomata, fibromyomas)
These are the most common tumours of the genital tract. A uterine fibroid is composed of smooth muscle bundles interspersed with strands of connective tissue, surrounded by a thin capsule (Box 36.1). The tumour may arise in any part of the Müllerian duct, but occurs most often in the myometrium, where several may develop simultaneously. The tumour may vary from the size of a pea to that of a football.
| What are they? | Encapsulated smooth muscle fibres interspersed with strands of connective tissue usually developing in the myometrium. They may remain intramural or grow outwards or into the uterine cavity. Dependent on an intact blood supply |
| Aetiology | Unclear |
| Prevalence | Increases from 5% to 20% of women during their reproductive years. More common in nulliparous women and those of low parity. Very slow growing in response to oestrogen. Regress after menopause |
| Diagnosis | Examination and confirmatory ultrasound |
| Symptoms | Depend on size and position and are frequently symptomless. Two most common symptoms are abnormal vaginal bleeding, usually heavy and/or prolonged, and pelvic discomfort, crampy or pressure |
| Management | Depends on rate of growth, size, symptoms and desire for pregnancy
• Myomectomy to preserve fertility, possibly in conjunction with a GnRh analogue to shrink the tumour temporarily
|
| Outcome |
Hysterectomy is the treatment of choice for women comfortable with its psychological and physical sequelae
Myomectomy is associated with a 40% chance of successful conception and a 5% recurrence of the fibroid or menorrhagia
|
| Pregnancy complications | Early pregnancy bleeding, premature rupture of membranes, obstructed labour and postpartum haemorrhage |
Fibroids occur in about 5% of women during the reproductive years. They grow slowly and may only be detectable clinically in the fourth decade of life, when the incidence increases to about 20%. They are more common in nulliparous women or women who have had only one child.
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