Giant Sarcomatoid Carcinoma with Osseous Metaplasia from Urinary Bladder Diverticulum

Sarcomatoid carcinoma is an extremely rare aggressive tumor variant comprising about 0.3% of all primary tumors of the urinary bladder. We report a rare case of giant bladder sarcomatoid tumor arising from a bladder diverticulum. A 60-year-old male on evaluation for long-standing obstructive voiding symptoms with recurrent pyuria found to have renal failure and bladder mass with bilateral hydroureteronephrosis (HDUN) on ultrasound. Further radiologic evaluation revealed multiple bladder diverticulae and anteriorly displaced bladder with a large mass arising from one of the posteriorly located bladder diverticulum with extrinsic compression of both the distal ureters leading to severe bilateral HDUN. Rigid cystourethroscopy was not successful due to anteriorly displaced urethra. Tissue biopsy taken with flexible cystoscope revealed low-grade, noninvasive transitional cell carcinoma. After staging workup, bilateral percutaneous nephrostomy was performed initially for stabilization of renal function. This was followed by radical cystoprostatectomy with bilateral extended pelvic lymphadenectomy with ileal conduit diversion. Histopathology revealed high-grade muscle-invasive sarcomatoid variant of urothelial carcinoma with osseous metaplasia. It is imperative to recognize the rare variants of bladder tumors with different therapeutic and prognostic considerations and hence tailor the management of individual variant.