Accessory cavitated uterine mass: MRI features and surgical correlations of a rare but under-recognised entity.

• ACUM is rare, with delayed diagnosis in young women with severe dysmenorrhoea. Pelvic MRI facilitates timely diagnosis and appropriate curative fertility-sparing laparoscopic resection. • Quasi-systematically located under the uterine round ligament insertion, ACUM may be intramyometrial and/or in the broad ligament. • On MRI ACUM resemble a non-communicating functional accessory horn within a normal uterus; the mass, most often round-shaped, had a central haemorrhagic cavity surrounded by a regular ring which had the same low signal compared to the uterine junctional zone.