[PLASMACYTOID UROTHELIAL CARCINOMA OF THE BLADDER WITH MASSIVE ASCITES: A CASE DEMONSTRATING SIGNIFICANT RESPONSE TO GEMCITABINE-CISPLATIN THERAPY].

We report a case of plasmacytoid urothelial carcinoma (PUC) of the bladder associated with massive ascites that showed a notable and temporary response to gemcitabine and cisplatin (GC) chemotherapy. A 69-year-old male underwent initial transurethral resection of the bladder tumor (TURBT) in August 202X-5. By December 202X-3, he had received four TURBT procedures and two courses of intravesical Bacillus Calmette-Guérin therapy. Histopathological examinations consistently revealed non-muscle-invasive urothelial carcinoma (pT1), and imaging studies showed no evidence of distant metastasis. However, the patient discontinued follow-up and treatment in May 202X-2. In October 202X, he presented with abdominal distension. Computed tomography revealed a large volume of ascitic fluid. Cytological analysis of the ascites indicated malignant cells consistent with urothelial carcinoma, prompting referral to our department in November 202X. Cystoscopy showed no evidence of intravesical tumor recurrence. A diagnostic laparoscopy performed in December 202X revealed diffuse peritoneal dissemination, and biopsy of an omental lesion confirmed peritoneal metastasis of PUC. GC chemotherapy was initiated in January 202X+1. The ascites volume markedly decreased after treatment initiation, and CT imaging after five courses of GC therapy showed complete resolution of the ascites. Due to chemotherapy-induced fatigue, treatment was temporarily discontinued. Three months later, ascites reaccumulated, and GC therapy was resumed in October 202X+1, again leading to a reduction in ascites. However, by March 202X+2, after completing 10 courses of GC therapy, the patient experienced a recurrence of ascites and developed small bowel dilation. Conservative management was provided for suspected ileus. A single cycle of pembrolizumab was administered, but the patient's condition progressively deteriorated, necessitating transition to palliative care. Although PUC is generally considered resistant to conventional chemotherapy, this case illustrates that GC therapy may provide temporary clinical benefit in selected patients. A brief review of the literature is also presented.