Carcinomatous Meningitis and Hydrocephalus in Plasmacytoid Urothelial Carcinoma of the Urinary Bladder With Extremely Elevated CA19-9 Levels

This case report describes a rare and aggressive presentation of plasmacytoid urothelial carcinoma (PUC) with carcinomatous meningitis, hydrocephalus, extensive organ involvement, and extremely elevated serum CA19-9 levels. Autopsy findings revealed that PUC of the urinary bladder origin caused carcinomatous meningitis and hydrocephalus, with exacerbation of hydrocephalus as the direct cause of death. Immunohistochemical studies confirmed the bladder origin of PUC, and PUC cells were positive for CA19-9, a tumor marker commonly associated with gastrointestinal malignancies, suggesting that the markedly high serum CA19-9 level was related to the tumor-producing mechanism.