Paraurethral Endometrioid Carcinoma Arising From Ectopic Endometriosis: A Case Report

Malignant transformation of endometriosis is rare and most commonly involves the ovary; transformation from paraurethral endometriosis is exceedingly rare.

A 73-year-old postmenopausal woman with prior ovarian endometrioma presented with dysuria and voiding difficulty. Positron emission tomography-computed tomography revealed a paraurethral mass at the bladder neck, whereas cystoscopy and urine cytology were normal. Transvaginal biopsy demonstrated adenocarcinoma; however, immunohistochemistry did not identify the primary site. After radical cystectomy with urethrectomy and partial vaginectomy, histopathology showed endometrioid carcinoma arising from paraurethral endometriosis with lymph node metastasis. Comprehensive genomic profiling identified alterations consistent with endometrioid/Müllerian-type carcinoma and compatible with endometriosis-associated carcinogenesis. Despite chemotherapy and immune checkpoint inhibitors, the patient died approximately 16 months after diagnosis.

Paraurethral endometrioid carcinoma is exceptionally rare. Accurate diagnosis relies on careful correlation of imaging with histopathology, while comprehensive genomic profiling provides corroborative molecular evidence.