Endometriosis: unusual cause of groin swelling.

DESCRIPTION A 36-year-old woman presented with crampy lower abdominal pain and a lump in her left groin. The lump present for 3 years and has slowly increased in size with occasional episodes of tenderness. Her medical history includes hysterectomy for fibroids. Examination revealed a 2×2 cm groin swelling lateral and superior to the pubic tubercle. CT revealed a solid lump above the inguinal ligament (figure 1). Ultrasound (US) demonstrated a solid mass with heterogeneous echogenic appearance (figure 2). Biopsy of the lesion revealed endometrial tissue. She declined surgical excision and gynaecology follow-up was arranged. Extrapelvic endometriosis is an uncommon disease entity. The gastrointestinal tract is the commonest site, while endometriosis presenting in the groin is rarely seen. The lump may be painful with cyclical exacerbation or painless with only catamenial symptoms. The lump may fluctuate in size with menstruation or exhibit haemorrhagic tendency. The pathogenesis of groin endometriosis is believed to be either secondary to local spread from retrograde menstruation, systemic spread (lymphatic or haematogenous) or coelomic metaplasia. Coelomic metaplasia is believed to be the cause in women who have underwent hysterectomy and are not taking hormone replacement therapy as in our case. 1 2 US and CT are generally not diagnostic, however US features can be suggestive while CT will help define anatomy. Treatment options include expectant management, hormonal therapy or complete surgical excision with minimal spillage to avoid recurrence. Gynaecology referral is advised as pelvic endometriosis is frequently present concomitantly.