Malignant pleural mesothelioma in a young adult without asbestos exposure: a case report highlighting diagnostic pitfalls and literature review

Background: Malignant pleural mesothelioma (MPM) is a rare and aggressive malignancy typically associated with asbestos exposure in older adults. Its occurrence in young individuals without asbestos exposure poses significant diagnostic challenges, particularly in tuberculosis-endemic regions. Case presentation: We report the case of a 23-year-old man with no history of asbestos exposure who presented with progressive pleuritic chest pain, dyspnea, fever, and weight loss. Initial evaluation suggested tuberculous pleuritis, and empirical therapy was initiated. Imaging revealed diffuse nodular pleural thickening with loculated effusion. Ultrasound-guided pleural biopsy demonstrated epithelioid MPM, confirmed by immunohistochemical positivity for calretinin and WT-1 with TTF-1 negativity. Despite supportive care, the patient experienced rapid clinical deterioration and died within 1 week of histopathological confirmation. Genetic testing for BAP1 mutation was recommended but could not be performed due to rapid disease progression. Conclusion: This case underscores the importance of considering MPM in the differential diagnosis of pleural effusion in young adults, even in the absence of asbestos exposure. Early pleural biopsy and immunohistochemical evaluation are essential to avoid diagnostic delay, particularly in tuberculosis-endemic settings.