Benign cystic mesothelioma of the peritoneum: immunohistochemical and ultrastructural features in a child.

Benign cystic mesothelioma of the peritoneum is a well-defined but rare entity. A total of 35 instances have been reported, almost all in adults, the majority females. Cystic mesotheliomas have, until recently, been labeled cystic lymphangiomas or lymphohemangiomas. We report the case of a 14-year-old boy who, despite only subtotal resection of his abdominal mass, is well and recurrence free 9 months after surgery. The role of immunohistochemistry and electron microscopy in diagnosis is emphasized.