Descending Colon Metastasis of Renal Cell Carcinoma: An Unusual Site of Metastasis

Renal cell carcinoma (RCC) has a high metastatic potential. While metastasis to common sites like the lungs, liver, bones, and brain is well-documented, metastasis to the colon, particularly the descending colon, remains an uncommon occurrence. When RCC does metastasize to the gastrointestinal tract, it commonly spreads to the small bowel and stomach. There are few cases reported in literature involving RCC metastasis to the colon. The commonly affected areas within the colon include the rectosigmoid colon, splenic flexure, and transverse colon. We describe an 87-year-old male with a history of stage III RCC diagnosed three years ago, followed by left-sided nephroureterectomy, partial adrenalectomy, and perinephric lymph node dissection. He presented to the emergency department (ED) with melena and generalized abdominal pain for one week. Stool occult blood was positive. Computed tomography (CT) of the abdomen was significant for stable postsurgical changes related to prior left nephrectomy and colonic mass at the proximal descending colon. A colonoscopy revealed a necrotic appearing friable mass in the descending colon. The pathology of the mass revealed proliferated atypical cells positive for paired box 8 (PAX8), a cluster of differentiation 10 (CD10), RCC, and pan-cytokeratin and negative for caudal-type homeobox 2 (CDX2), thyroid transcription factor-1 (TTF-1), and a cluster of differentiation 68 (CD68), consistent with metastatic RCC.