Pseudocarcinomatous hyperplasia associated with primary lymphoma in the urinary bladder: a case report

A case of pseudocarcinomatous hyperplasia of the urothelium associated with primary extranodal marginal-type lymphoma of the urinary bladder in an 81-year-old man is described. To the best of our knowledge, this is the first report in the literature of a primary lymphoma of the bladder associated with pseudocarcinomatous hyperplasia of the urothelium, closely mimicking the nested variant of urothelial carcinoma. The lesion enters in the differential diagnosis with a collision tumor, which has been described rarely in the bladder.