Benign tumours, cysts and malformations of the genital tract

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Chapter 36 Benign tumours, cysts and malformations of the genital tract

Benign tumours or cysts may form in any part of the genital tract. Benign tumours occur most often in the uterus and most benign cysts occur in the ovaries. Malformations tend to involve the uterus and the vagina.

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.

Fig. 36.2 Differentiation of the female external genitalia (not to scale).

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.

Fig. 36.3 Haematocolpos due to imperforate hymen septum.

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.

Fig. 36.4 Common genital tract malformations.

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.

Fig. 36.5 The use of polyp forceps to secure and remove endometrial polyps.

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.

Box 36.1 Fibroids

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 • Relief from bleeding, anaemia • Wait and see • Myomectomy to preserve fertility, possibly in conjunction with a GnRh analogue to shrink the tumour temporarily • Hysterectomy