[CASE REPORT: COMPLETE RESECTION OF RETROPERITONEAL CYSTIC LYMPHANGIOMA AND SURROUNDING ORGANS].

A 65-year-old man was admitted to our institution with vomiting and right flank pain. Computed tomography (CT) imaging showed a 21-cm retroperitoneal multilocular cystic tumor which had been identified four years previously. It had increased from 17 to 21 cm. The initial diagnosis was cystic lymphangioma because it was a clear cystic tumor without a boundary or a solid component in the first CT, but later CT revealed an unclear boundary with surrounding organs suggesting malignancy. We decided to resect the tumor because it was symptomatic and might be malignant. The tumor was then resected along with surrounding organs because invasion was suspected. Pathological findings indicated a diagnosis of cystic lymphangioma with chronic inflammation and confirmed complete resection of the tumor. The patient has remained free of recurrence at one year after surgery. This experience indicates that cystic lymphangioma should be completely resected to prevent recurrence.