RESUMO
Undifferentiated carcinoma of the bladder is a rare malignancy with a poor prognosis. We present the case of an 81-year-old woman complaining of bladder irritation. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a bulky bladder tumor, which was diagnosed as cT4aN0M0. A transurethral resection of the bladder tumor revealed pT2 or higher urothelial carcinoma. The patient underwent total cystectomy with an ileal conduit diversion. Histological examination revealed a primary undifferentiated bladder carcinoma with a sarcoma component, pT3aN0M0. Postoperative adjuvant chemotherapy with gemcitabine plus carboplatin was administered. However, this regimen was discontinued after one course due to significant myelosuppression. Four months after total cystectomy, a pelvic tumor with suspected local recurrence was detected on CT. The patient was diagnosed with recurrent undifferentiated carcinoma with a sarcoma component by a transperineal ultrasound-guided biopsy. Local radiation therapy and immunotherapy with immune checkpoint inhibitors were prescribed. After three courses of immunotherapy with pembrolizumab, the primary tumor disappeared. Upon continuing immune checkpoint inhibitor treatment, the patient has maintained a complete response without tumor recurrence in the following six months.