Excision of an Unexpected Retroperitoneal Mass at Laparoscopy.

Neurofibroma is a benign soft tissue tumour of neural origin. Neurofibromatosis or Von Recklinghausen disease is an autosomal-dominant condition. Pelvic occurrence of a solitary neurofibroma is uncommon. A 54-year-old woman presented with a history of chronic back pain with occasional dyspareunia for 12 months. She had a hysterectomy and right salpingo-oophorectomy for endometriosis many years back. Clinical examination revealed fullness and tenderness at left vaginal vault. Pelvic ultrasonography revealed a 55x49x55mm mass suggestive of dermoid cyst. Magnetic resonance imaging findings were consistent with dermoid cyst. Intraoperatively, a retroperitoneal mass in the left pelvic sidewall was removed along with left fallopian tube and ovary. Histopathology revealed neurofibroma. There was no recurrence on follow-up. Solitary, de novo, retroperitoneal pelvic neurofibroma is very rare. A lack of familiarity with the anatomy and pathogenesis of retroperitoneal masses often leads to a diagnostic conundrum due to overlapping imaging findings. A possibility of neurofibroma or schwannoma should be kept in mind while evaluating pelvic and/or adnexal masses.