Urachal mucinous cystic tumor of low malignant potential: a report of a rare case with literature review

Neoplasms originating from the urachus are exceptionally uncommon, comprising only 0.17% of all bladder neoplasms. Among these, the mucinous cystic tumor of low malignant potential (MCTLMP) is particularly rare, with only 25 documented cases in medical literature. Despite their rarity, it is essential to identify MCTLMPs given the possibility of severe complications. Fortunately, surgical removal offers promising cure rates. In this report, A 40-year-old female patient presented to the hospital with abdominal pain. Subsequently, a CT scan showed a 9-cm cystic mass pressing the bladder. The lesion was surgically excised and histopathological examination was performed. Grossly, the specimen consisted of a cyst with a smooth external surface and mucinous content. Microscopically, the cyst was lined by columnar mucinous epithelial cells that included basally-located hyperchromatic nuclei and scattered Goblet cells consistent with an intestinal phenotype. The epithelial cells show mild atypia with focal papillary formations and flattening due to compression. Immunohistochemically, the epithelial tumor cells expressed cytokeratin 20, CDX2, beta-catenin (membranous); and were negative for cytokeratin 7. The location, histopathological, and immunohistochemical findings were consistent with a diagnosis of MCTLMP. In this report, we present an instance of urachal MCTLMP, which represents less than 30 cases documented in the medical literature. This case study marks the importance of early identification of MCTLMP due to their potential for severe complications, despite the tumor’s low malignant potential and to exclude more aggressive tumors with areas of intraepithelial or invasive carcinoma.