[A Case of Renal Cell Carcinoma with Small Bowel Metastasis Accompanied by Invagination]

We report a case of small bowel metastasis from renal cell carcinoma (RCC) in a woman in her 70s. In 20XX, she underwent a laparoscopic left nephrectomy for left-sided RCC (pT3bN0M0). Three and a half years later, she presented to the emergency department with recurrent vomiting. Contrast-enhanced computed tomography (CT) revealed a suspected small bowel tumor with intussusception and associated lymphadenopathy. Laparoscopic partial resection of the small intestine was performed, and pathological examination confirmed metastatic RCC in both the small bowel and regional lymph nodes. One month later, positron emission tomography-computed tomography (PET-CT) showed increased uptake in the mesenteric lymph nodes, suggesting residual disease. As a result, systemic therapy with ipilimumab and nivolumab was initiated. After four cycles of treatment, follow-up imaging demonstrated complete resolution of the residual lesions. Isolated small bowel metastasis from RCC, which was observed in this case, is relatively rare.