Mesothelial and related neoplasms in children and adolescents: a clinicopathologic and immunohistochemical analysis of eight cases.

Mesothelioma is a neoplasm that occurs infrequently in childhood; only an estimated 2-5% of all cases present in the first two decades of life. The diagnosis may be perplexing because of its rarity and its pathologic similarities to other papillary or spindle cell neoplasms in the pediatric age group. We have studied eight cases of mesothelial or submesothelial-derived neoplasms of pleural (four cases) and peritoneal (four cases) origin in patients 4 to 17 years of age at diagnosis. Microscopically, six were epithelial, with papillary, tubuloglandular, and solid patterns. Two tumors were predominantly fibrous appearing, one a localized pleural fibroma and the other a diffuse pleural sarcomatoid mesothelioma. All of the tumors were immunoreactive for vimentin, and all except the pleural fibroma stained for either cytokeratin, epithelial membrane antigen, or both. None reacted with antibodies to carcinoembryonic antigen, placental alkaline phosphatase, or Leu-M1. At last follow-up, three patients were dead of tumor, three were alive and well, and two had been recently diagnosed and were undergoing treatment. These results indicate that the immunohistochemical profile delineated for mesothelioma in adults is equally applicable to mesothelial neoplasms in younger patients and is useful in establishing a diagnosis. The prognosis for malignant mesothelioma in childhood appears to be as unfavorable as the adult counterpart, with the possible exceptions of certain clinicopathologic subtypes.