Urachal mucinous cystic neoplasm of low malignant potential – a rare entity

Abstract

Mucinous cystic neoplasms of the urachus are exceedingly rare, yet likely under recognised tumours with a morphological spectrum of malignancy similar to mucinous ovarian neoplasms. We report a case of a urachal cyst identified incidentally in an otherwise well 35-year-old man. Radiologically and macroscopically, the cyst was intact, unilocular, and filled with copious mucin. It had a smooth inner surface and no patent luminal continuity with the urinary bladder. Histologically, the cyst wall comprised a single layer of mucinous intestinal-type epithelium forming tufted pseudopapillary structures with low-grade cytological atypia and scattered mitoses.