Pseudomesotheliomatous lung cancer mimicking malignant pleural mesothelioma: A case report

Pseudomesotheliomatous lung cancer (PML) is an uncommon type of primary lung cancer that mimics malignant pleural mesothelioma (MPM); however, data on this specific presentation remain scarce. We reported a 47-year-old Thai female presenting with right-sided chest pain, progressive dyspnea, and weight loss for three months. A computed tomography scan revealed extensive circumferential nodular pleural thickening and multiple irregular pleural-based masses affecting the right hemithorax, along with multiple foci of calcified pleural plaques in the bilateral hemithoraces. These findings raised a concern for malignant pleural mesothelioma with past asbestos exposure. However, a pleural biopsy later confirmed adenocarcinoma of the lung through immunohistochemical studies (positive for thyroid transcription factor-1 and negative for calretinin). Despite receiving five cycles of chemotherapy, her condition deteriorated, and she died approximately ten months following the initial diagnosis. In conclusion, PML with pleural plaques is rarely reported, and immunohistochemistry staining is imperative for an accurate diagnosis.