[A case of papillary renal cell carcinoma mimicking a hemorrhagic renal cyst].

A right renal cyst was found in a 69-year-old man with stage IV chronic kidney disease on abdominal ultrasonography performed to investigate a right upper abdominal swelling. Aspiration cytology of the cyst revealed no malignancy, but malignancy could not be ruled out on magnetic resonance imaging because of the cyst's wall thickness and heterogeneous contents. At one-year of follow-up, emergent abdominal surgery was performed due to incidental perforation of ascending colon diverticulitis. At that time, cystic fenestration was performed because the large renal cyst obstructed the operative procedure. Pathological examination showed type-1 papillary renal cell carcinoma, and radical nephrectomy was performed after the patient's general condition improved. Hemodialysis was started after the operation, and there has been no disease recurrence for two years.