Unusual Presentation of Urothelial Carcinoma of the Bladder With Noncontiguous Rectal and Diffuse Muscular Skeletal Metastases

Abstract

AN 83-year-old man presented with frequent bowel movements and weight loss in the last 6 months. History was remarkable for hypertension and diabetes mellitus. Digital rectal examination revealed a tumor 3 cm from the anal verge, which was subsequently confirmed by rectoscopy. Biopsy revealed poorly differentiated carcinoma. The tumor cells stained strongly positive for CK7, weakly positive for CK20, and negative for CDX-2 and S-100. Therefore, primary adenocarcinoma of the colon was less likely and tumor growth of urothelial origin was suspected. Subsequent computerized tomography (CT) of the abdomen showed thickening of the right posterior wall of the bladder and noncontiguous circumferential thickening of the rectal wall (figs. 1 and 2). CT also revealed extensively infiltrative, strong enhancing lesions in multiple skeletal muscles, including bilateral psoas major, quadratus lumborum, iliacus, gluteus medius/minimus, obturator externus, quadratus femoris and adductor brevis/magnus. Cystoscopic biopsy of the bladder tumor confirmed high grade urothelial carcinoma. Ultrasound biopsy was performed for the skeletal muscle lesion and the result was consistent with metastatic urothelial carcinoma. The patient was treated with chemotherapy. Bladder urothelial carcinoma often metastasizes to regional lymph nodes, liver, lung and bone. The lower gastrointestinal tract is usually involved by direct tumor invasion. Noncontiguous rectal metastasis from urothelial carcinoma presenting as an annular rectal tumor is rare. 1 This case had concomitant diffuse skeletal muscle metastasis, which is an even rarer presentation of urothelial carcinoma. 2 Metastatic muscular lesions of urothelial carcinoma origin usually show low density and ring enhancement on CT. 3 However, in