Clinical overview
Cysts of the female genital tract are among the commonest findings in gynaecological practice, ranging from incidental, asymptomatic lesions found on a routine speculum examination or pelvic ultrasound to painful, infected or — rarely — malignant masses. A cyst is not a diagnosis but a morphological category (a fluid-filled, epithelium- or membrane-lined cavity), and its clinical meaning depends entirely on where it sits along the tract, what lines it, what fills it, and what gave rise to it. The same word — "cyst" — covers a benign embryological remnant on the vaginal wall, a tense Bartholin abscess in the vulva, a physiological follicular cyst on the ovary, and a unilocular serous cystadenoma that may harbour borderline change. The gross and microscopic features are what separate the trivial from the sinister at the bedside, on the scan, and down the microscope.
The pathological description carries the weight here — gross morphology, lining epithelium, contents, and the developmental or acquired mechanism for each lesion, site by site from vulva to ovary. But every cyst still demands a coherent assessment (is it benign or does it need malignancy work-up?) and a management principle. In the South African setting two factors recur: the very high background prevalence of HIV, which alters the natural history of infective and HPV-driven lesions and raises the index of suspicion for cervical pathology; and the reality of NHLS histopathology turnaround and access, which shapes how aggressively we biopsy versus observe. WHO-2020 pathology terminology is used throughout. The material links closely to Genital anatomy, Fibroids, Adnexal mass in pregnancy, Ultrasound malignancy signs and the screening pathway in Cervical screening SA.
Core knowledge
A practical way to organise the pathology is developmental (embryological remnant) versus retention versus inflammatory/infective versus functional (physiological) versus neoplastic, applied at each anatomical site. The defining features are always the same triad: lining epithelium, wall, and contents.
Vulval cysts
Figure D1.1 — Genital-tract cysts by site: vulva (Bartholin, epidermoid, Skene), vagina (Gartner, Müllerian), cervix (Nabothian) and adnexa — location as the first diagnostic clue.
- Bartholin gland cyst. The greater vestibular (Bartholin) glands lie at 4 and 8 o'clock at the posterior introitus; they secrete mucus through a duct opening into the vestibule. Obstruction of the duct produces a retention cyst — a unilocular, tense swelling in the posterior labium majus, lined by transitional/squamous epithelium of the duct (the acinar mucinous epithelium is usually destroyed by pressure atrophy). Contents are sterile mucoid fluid. Secondary infection produces a Bartholin abscess — painful, fluctuant, erythematous, often polymicrobial (anaerobes, coliforms; historically Neisseria gonorrhoeae and Chlamydia trachomatis, so STI co-testing matters in the SA/HIV context). A solid or persistent "Bartholin mass" in a woman over 40 must raise the possibility of Bartholin gland carcinoma and be biopsied, not simply drained.
- Epidermal (epidermoid) inclusion cyst. The commonest vulval cyst overall: a keratin-filled cyst lined by stratified squamous epithelium with a granular layer, often from traumatic implantation of epidermis (e.g. after episiotomy or female genital cutting). Gross: small, firm, yellow-white, cheesy keratin content.
- Cyst of the canal of Nuck (hydrocele of the canal of Nuck). A persistent processus vaginalis (the female homologue of a patent processus) producing a cyst in the inguinal/labial region lined by mesothelium — a peritoneal remnant.
- Mucous (mucinous vestibular) cysts of the vestibule, lined by columnar mucinous epithelium of urogenital sinus origin.
Vaginal cysts
Figure D1.2 — Origin explains location: mesonephric/Wolffian (Gartner), paramesonephric/Müllerian and epithelial-inclusion cysts, and the lining/contents each produces.
- Gartner duct cyst. The classic mesonephric (Wolffian) remnant: arises from the embryonic mesonephric duct running along the anterolateral vaginal wall. Lining is low cuboidal/columnar, non-mucinous, non-ciliated epithelium; contents are thin and watery. Usually small and asymptomatic; large ones may cause dyspareunia or obstruct. Their anterolateral position and non-mucinous lining distinguish them from Müllerian cysts.
- Müllerian (paramesonephric) cyst. Lined by mucinous, ciliated or endocervical-type epithelium, reflecting Müllerian origin; can occur anywhere in the vagina.
- Epidermal inclusion cyst. The commonest acquired vaginal cyst, typically posterior wall, at the site of previous obstetric trauma or surgical repair; squamous-lined, keratin-filled — the same pathology as its vulval counterpart.
- Endometriotic cyst / implant in the vaginal wall (rare) — lined by endometrial glands and stroma with haemosiderin-laden macrophages.