Nonpleural mesotheliomas: mesothelioma of the peritoneum, tunica vaginalis, and pericardium.

Mesotheliomas are tumors that arise from the mesothelial cells of the pleura, peritoneum, pericardium, or tunica vaginalis. Although the number of new mesothelioma cases diagnosed each year in the United States seems to be leveling off or decreasing, several other countries are projected to have continued increased incidence of mesothelioma over the next several years. Of the approximately 2500 new cases of mesothelioma in the United States each year, most are pleural mesotheliomas. The peritoneum is the second most common site of mesothelioma development and accounts for approximately 10% to 20% of all mesotheliomas. Mesotheliomas that involve the pericardium or originate from the tunica vaginalis are rare tumors. Given the rarity of these tumors, it is difficult to obtain precise information regarding their incidence, natural history, and optimal management.