Pulmonary sarcomatoid carcinoma mimicking pleural mesothelioma

Introduction: Pulmonary sarcomatoid carcinoma (PSC) is an extremely rare biphasic tumor characterized by a mixture of malignant epithelial and mesenchymal cells. Owing to the rarity, as well as the lack of typical manifestations and imaging signs, the rate of misdiagnosis is high. Herein, we present a case of PSC misdiagnosed as pleural mesothelioma in a 59-year-old man. Patient concerns: A 59-year-old man presented with recurrent coughing, fever, and chest pain. Diagnosis: Chest computed tomography showed 2 large and dense masses involving the inferior lobes of right lung, along with slight irregular pleural thickening and a small amount of effusion. Interventions: Chest computed tomography-guided tumor biopsy was performed. PSC was confirmed based on histopathology and immunohistochemistry. The patient refused treatment due to economic reasons. Outcomes: The patient developed adrenal, multiple lung and brain metastasis. The overall survival time was 11 months. Conclusions: PSC, despite its rarity, should be considered in the differential diagnosis of lung cancer. Besides, biopsy, histopathology, and specific immunohistochemical staining of larger tissue specimens can be contributing to the accurate diagnosis of PSC.