Case report: a left upper quadrant complex cystic mass.

A 61-year-old woman presented with left upper quadrant/flank pain and increasing abdominal girth. CT scan showed a large complex, multi-cystic lesion in the left abdomen. Laparotomy revealed a large retroperitoneal mass attached to the left kidney. Left nephrectomy was performed and pathology demonstrated a benign cystic nephroma. Surgical oncologists should be aware of this rare renal lesion as the clinical and radiographic presentation may mimic other intra-abdominal cystic lesions.