Localized Mesothelioma is an exceptionally rare and clinically distinct variant of malignant mesothelioma characterized by a solitary, well-circumscribed tumor mass confined to a specific anatomic site—most commonly within the pleura or peritoneum—without evidence of diffuse serosal involvement or metastatic spread at diagnosis.
Unlike Diffuse Malignant Mesothelioma, which spreads extensively across mesothelial surfaces, localized mesothelioma remains restricted in growth, often mimicking benign or other localized malignancies. It may present as either localized malignant mesothelioma (true neoplastic origin) or as well-differentiated papillary mesothelioma, a low-grade neoplasm with indolent behavior.
Histologically, it may appear similar to the epithelioid subtype and requires immunohistochemical analysis for differentiation. Diagnosis is often incidental or discovered during imaging or surgical evaluation for unrelated symptoms such as chest pain or abdominal masses.
Although asbestos exposure is a known risk factor, its association with localized mesothelioma is less definitive than in the diffuse form. Prognosis is typically more favorable due to the potential for complete surgical resection, with long-term survival possible in certain cases. However, misdiagnosis remains a critical risk due to its rarity and overlap with other neoplasms.