Abstract
Large-cell undifferentiated carcinoma of the urinary bladder is an extremely rare and aggressive neoplasm. We present a unique case of painless gross hematuria and a past surgical history of cystolithotomy. The patient underwent transurethral resection of the bladder tumor, which revealed high-grade urothelial cell carcinoma with lamina propria involvement. Subsequent radical cystoprostatectomy with orthotopic neobladder urinary diversion and pelvic lymphadenectomy was performed, and the postoperative pathologic examination indicated large-cell undifferentiated. This case report highlights the importance of accurate diagnosis and management for this rare malignancy and adds to the limited existing literature on Large-cell undifferentiated carcinoma.