Occult renal involvement by sigmoid colon adenocarcinoma presenting as spontaneous renal rupture: a case report

Spontaneous renal rupture (SRR) is a rare nontraumatic emergency, usually associated with renal neoplasms, vascular lesions, infection, coagulopathy, or obstruction. Diffuse malignant infiltration may be missed when it does not form a discrete mass. A 45-year-old man previously treated for sigmoid colon adenocarcinoma had chronic left ureteral obstruction and presented with sudden severe left flank pain and gross hematuria. Contrast-enhanced CT showed left renal rupture with a large perirenal and retroperitoneal hematoma, a chronic left ureteral stent, and moderate right hydroureteronephrosis. No enhancing renal or ureteral mass was visible. Hemoglobin was 108 g/L on arrival, and the extent of the hematoma raised concern for ongoing hemorrhage. Selective renal arterial embolization was considered, but open nephrectomy was chosen because the left kidney was chronically compromised and tumor-related rupture could not be excluded. The right ureter was stented first to protect the remaining renal unit. Gross examination identified a dorsal cortical tear but no discrete tumor. Histology disclosed diffuse poorly differentiated carcinoma with extensive necrosis and invasion of renal hilar vessel walls. Immunohistochemistry supported colorectal origin. Urinary tract and systemic recurrence followed, and the patient died of multiorgan failure in June 2024.Diffuse malignant renal involvement should remain in the differential diagnosis when a patient with previous colorectal cancer develops unexplained nontraumatic renal or perirenal hemorrhage, even if imaging shows no mass. If nephrectomy is required in the presence of contralateral upper urinary tract obstruction, drainage of the remaining renal unit should be planned beforehand.