Malignant peritoneal mesothelioma in a child.

Malignant mesothelioma of the peritoneum in young children is very rare. We describe a fatal case in a child who presented with groin swellings at age 9 years 9 months. Initial histology simulated an inflammatory mesothelial hyperplasia. After a prolonged response to steroids, masses that had the histology of mixed epithelial and mesenchymal malignant mesothelioma became apparent in the abdomen and pleura. There was no significant response to subsequent chemotherapy. No definite etiologic factors were identified. Pathologists should be aware that this tumor may rarely present in young children and may have a significant inflammatory component. Etiologic considerations are discussed.