RESUMEN
Adenocarcinomas account for 0.5-2% of all bladder cancers. Urachal carcinoma is a rare neoplasm which represents 0.01% of all cancers in adults and account for one third of bladder adenocarcinomas. A 65-year-old white man with an urachal mucinous adenocarcinoma is reported. None of the known predisposing risk factors for bladder cancer -such as tobacco use and professional exposure to chemicals -were identified in his past medical history. The patient suffered from multiple sclerosis for almost 11 years and in the last 6 years he was treated with low doses of mitoxantrone. He underwent a partial cystectomy and en block excision of the umbilical ligament and remains disease-free after one year. The development of this rare neoplasm should not be clearly dissociated from multiple sclerosis, either aetiologically sharing an unidentified common causative factor or due to its treatment with mitoxantrone.