A case of mucosal-associated lymphoid tissue lymphoma of the urachus.

Introduction: Urachus carcinoma is a rare malignancy with an aggressive potential and a poor prognosis, and evidence is limited for its diagnosis and treatment.

Case Presentation: A 75-year-old man underwent fluorodeoxyglucose positron emission tomography/computed tomography for staging prostate cancer, and a mass (standardized uptake value max 9.5) was observed on the outside of the urinary bladder dome.