Spontaneously ruptured renal cell carcinoma during hemodialysis in two patients with end-stage renal disease.

Spontaneously ruptured renal cell carcinoma (RCC) in end-stage kidney disease is very rare. Preoperative diagnosis is difficult because of the relatively small tumor size, associated hematoma, and surrounding acquired cysts. Two middle-aged men who were maintained on hemodialysis (HD) for over 10 years suddenly developed flank pain during HD. Computed tomography scans revealed an enhancing ruptured renal mass in one patient, and no obvious tumor lesion except for a hematoma in the other, both of which were later confirmed as RCCs by pathologic specimens.