EP185 - The Blue Zebra: Metastatic Clear Cell Renal Cell Carcinoma to the Colon; A Case Series

Purpose/Background: Colonic metastasis from clear cell renal cell carcinoma (ccRCC) is exceedingly rare and often misdiagnosed, being commonly mistaken for primary colorectal malignancy. We present two cases of ccRCC metastasis to the colon, each demonstrating drastically different clinical presentations but similar tumor appearance on colonoscopy: the first, being entirely asymptomatic and the second, uniquely presenting with persistent hiccups.

Methods/Interventions: Case 1: A 65-year-old male with a history of right nephrectomy for ccRCC eight years prior presented with intractable hiccups, a 10-lb weight loss, and profound anemia (Hgb 4.2 g/dL). CT imaging revealed a large intussuscepted mass at the splenic flexure. Colonoscopy identified a nearly fully obstructive and 6.5cm hemorrhagic fungating lesion with smooth surface and blue hue (fig 1). Biopsy was inconclusive due to necrosis. Surgical resection of a 14 cm segment of colon confirmed metastatic ccRCC with submucosal and muscularis propria invasion. All 20 lymph nodes were negative for malignancy.

Case 2: A 73-year-old female, 13 years post-nephrectomy for ccRCC, was asymptomatic but had significant anemia and a positive Cologuard test. CT imaging was unremarkable. Colonoscopy revealed a 5.2 cm fungating mass at the ileocecal valve with smooth surface and blue hue (fig.2). Biopsy was again nondiagnostic, but surgical resection revealed a metastatic ccRCC lesion. Immunostaining was positive for PAX8, RCC1, and CAIX. No lymphatic or pericolonic invasion was observed, all 24 lymph nodes were benign.

Results/Outcomes: Grossly, both masses were large, fungating and polypoid in nature, with smooth surface and blue hue, appearing different from colonic adenocarcinoma. Both patients had profound anemia despite different presenting clinical symptoms. Histologic features and immunostaining confirmed ccRCC origin in both cases. Both patients underwent successful resections with primary anastomosis and had uncomplicated recoveries. In both patients, surgical management not only provided symptomatic relief but also allowed for definitive diagnosis and staging. The absence of lymph node metastasis and the isolated nature of both lesions is a favorable prognostic factor, and resection may offer survival benefits in select patients.

Conclusion/Discussion: Colonic metastasis from ccRCC is rarely reported and can occur years after nephrectomy. Presentations vary from nonspecific symptoms like anemia, or uniquely even hiccups. Biopsies may be nondiagnostic due to tumor necrosis, but a high index of suspicion should exist with a fungating, smooth, blue hued tumor in a patient with a history of ccRCC regardless of the time since ccRCC treatment. Recognizing these rare presentations prevents misdiagnosis and delays in treatment. Surgical resection remains the standard for symptomatic or solitary lesions and may offer survival benefit in selected patients.

Figure 1: Colonoscopy image
6.5cm hemorrhagic fungating lesion with smooth surface and blue hue
Figure 2: Colonoscopy image
5.2 cm fungating mass at the ileocecal valve with smooth surface and blue hue