In rare cases, pseudomesotheliomatous tumors spread diffusely within the pleura to form an encasing mass, which may be confused with diffuse malignant mesothelioma (DMM). A 73-year-old male presented with chest pain, dyspnea and a significant loss of weight and appetite. His radiological and clinical features suggested DMM. However, immunohistochemical studies revealed a primary squamous cell cancer of the lung. To the best of our knowledge, this is the first case report of pseudomesotheliomatous primary squamous cell lung cancer in Turkey, and also the seventh case worldwide. The present report aims to present this case, along with a review of the medical literature.