[A Case of Retroperitoneal Serous Cyst Treated by Open Fenestration : A Case Report].

A 47-year-old woman came to our hospital with left lower abdominal pain in April 2013. An abdominal computed tomographic (CT) examination revealed left hydronephrosis secondary to a 7 cm retroperitoneal cyst near the left common iliac artery and ureter. Serum tumor markers including CEA, CA19-9, and CA125 were negative. Although CT guided needle aspiration of the cyst successfully relieved severe left flank pain, the cyst again increased in size, causing left hydronephrosis, though examinations for fluid tumor markers and cytology were negative. Two months later, the patient underwent open fenestration. The final pathological results demonstrated a mesothelial cyst without malignant findings. Six months after the operation, the patient was doing well without recurrence of symptoms.