Hidden endometrial cancer due to vaginal obliteration associated with lichen sclerosus/lichen planus.

An elderly postmenopausal woman with untreated vulvar lichen sclerosus and lichen planus (LP) overlap presented with abdominal pain, constipation and urinary symptoms. Severe vulvovaginal scarring caused complete vaginal obliteration, preventing conventional speculum examination and transvaginal ultrasonography. Endorectal and abdominal ultrasonography revealed a large cystic pelvic mass. Urgent laparotomy identified extensive haematocolpos and uterine distension due to complete outflow obstruction. The patient underwent a hysterectomy, bilateral salpingo-oophorectomy and subtotal colpectomy. Histopathology confirmed Stage International Federation of Gynecology and Obstetrics (FIGO) IIB endometrioid endometrial carcinoma with mismatch repair deficiency while the vaginal tissue showed benign fibrosis. Postoperatively, she received topical corticosteroids for her vulvar disease and remained recurrence-free at a 24-month follow-up. This case emphasises that advanced vulvovaginal scarring can mask gynaecological malignancies and obstruct conventional diagnostics, necessitating alternative imaging and prompt surgical intervention to optimise outcomes.