Metastatic clear cell renal cell carcinoma presenting as multiple colonic polyps

Area of Science:

• Oncology
• Gastroenterology
• Pathology

Background:

• A 92-year-old male with a history of right nephrectomy for renal cell carcinoma (RCC) underwent routine gastrointestinal surveillance.
• The patient was asymptomatic with no current gastrointestinal complaints.

Observation:

• Lower gastrointestinal endoscopy revealed four distinct polyps in the ascending colon, hepatic flexure, and sigmoid colon.
• All identified polyps were successfully removed via snare polypectomy.

Findings:

• Histological examination of the polyps demonstrated sheets of clear cells within the lamina propria, arranged in a nested pattern with a prominent vascular network.
• Immunohistochemical analysis confirmed the neoplastic cells were positive for low-molecular-weight cytokeratin, CD10, and vimentin.
• Morphological and immunophenotypic features were consistent with metastatic clear cell renal cell carcinoma.

Implications:

• This case presents an exceptionally rare instance of recurrent renal cell carcinoma manifesting as multiple, separate colonic polyps.
• The findings underscore the importance of considering metastatic disease in the differential diagnosis of colonic polyps, even years after primary tumor resection.
• This unusual presentation highlights a potential, albeit infrequent, pathway for late recurrence of renal cell carcinoma in the gastrointestinal tract.