Benign cystic mesothelioma in a child.

An 11-month-old male presented with massive ascites and respiratory distress with no known etiology. Laparotomy confirmed ascites with multiple large cystic structures that originated in the left retroperitoneum. Grossly, it resembled lymphangioma; however, histopathologic diagnosis was benign cystic mesothelioma (BCM), an entity that presents mainly in women of childbearing age. After resection, the child had 2 recurrences for the following year, the first of which required resection. He also underwent resection of a congenital cystic adenomatoid malformation of the right lung. Only 4 other confirmed pediatric cases of BCM have appeared in the literature. As BCM may be confused with lymphangioma, it is important to be aware of BCM because of its propensity for recurrence and possible malignant degeneration.