Imaging Manifestations of Accessory Cavitated Uterine Mass-A Rare Mullerian Anomaly.

Accessory cavitated uterine mass (ACUM) is an uncommon and under-recognized entity with distinct imaging characteristics and causing significant patient distress. Differentiating it from its other clinical and radiological differentials is therefore extremely important and prevents delay in surgical management which is the treatment of choice.  The aim of the study is to describe the MRI appearance of the surgically and pathologically proven ACUM cases from our institution in the last 2 years.  This is a retrospective study in a tertiary care hospital in South India.  We reviewed the clinical presentations and imaging findings of seven surgically proven cases of ACUM qualifying the proposed diagnostic criteria.  All patients presented with chronic pelvic pain, dysmenorrhea, and prolonged post-menstrual pain. MRI in all seven cases showed an intramural, noncommunicating, and cavitating lesion near the uterine cornua with internal contents similar to that of endometrioma. Although the cavity was lined by endometrium in all the cases (proven in pathology), it was well appreciable on MRI in only five cases. The rest of the uterine myometrium and main endometrial cavity were normal with no features of adenomyosis.  MRI is a reliable diagnostic tool for accurate diagnosis of ACUM, and more importantly, in distinguishing it from other causes of chronic pelvic pain like adenomyosis and endometriosis and other imaging differentials like adenomyoma, noncommunicating uterine horn, and degenerating leiomyoma.