[A Case of PT1 Plasmacytoid Variant Bladder Cancer Treated by Bladder Conserving Therapy]

Plasmacytoid variant bladder cancer is a highly malignant subtype associated with a high propensity for invasion, metastasis and poor prognosis. Among approximately 100 reported cases, most were diagnosed at an advanced stage and only 10 were diagnosed at a non-muscle-invasive stage. Due to the limited data on clinical features of non-muscle-invasive plasmacytoid variant bladder cancer, its treatment has not been established. We report a long-surviving patient with pT1 plasmacytoid variant bladder cancer in whom the bladder was conserved after detailed pathological examinations of the transurethral resection (TUR) specimen and intensive follow-up. A 65-year-old man presented with macroscopic hematuria. Cystoscopy revealed a nodular tumor 11 millimeters in diameter and no metastasis was observed on computed tomography. The histopathological diagnosis of the TUR specimen was pT1 plasmacytoid variant urothelial carcinoma of the bladder. Microvascular invasion was not found by immunohistochemical staining and histopathological examination of the specimen from the second TUR indicated no residual cancer. The patient strongly desired bladder conservation and additionally underwent intravesical instillation therapy with 40 mg of mitomycin C weekly for 6 consecutive weeks. Follow-up cystoscopy demonstrated 3 small papillary tumors 12 months after intravesical instillation therapy, but histopathologically, the recurrent tumors were pTa with pTis urothelial carcinomas without plasmacytoid components. To treat pTis disease, he subsequently underwent intravesical BCG instillation therapy. The plasmacytoid variant bladder cancer has not recurred for 26 months since the initial diagnosis. Non-muscle-invasive and localized plasmacytoid variant bladder cancer may be treated with bladder conserving therapy.