Malignant Mesothelioma Presenting as a Gradually Enlarging Pneumothorax

Malignant mesothelioma is an extremely aggressive tumor arising from the pleura with median survival of approximately 9–12 months. It can rarely present as a spontaneous pneumothorax. Less than 35 cases of malignant mesothelioma presenting as spontaneous pneumothorax have been reported in the literature. Pathology may show florid mesothelial hyperplasia. We herein report a case of mesothelioma presenting as a pneumothorax that gradually enlarged over a one-year period and also review the relevant literature. A 69-year-old man was referred to pulmonary clinic for a gradually enlarging right-sided pneumothorax. A year and a half prior to clinic visit, the patient had experienced 3 days of vomiting associated with retching. This was followed by a nonproductive cough without fever or chest pain. A chest radiograph revealed a small right-sided pleural effusion. A chest CT scan confirmed a small effusion and also showed a small right lower lobe infiltrate. An esophageal perforation was ruled out. He was treated with a 1-week course of oral fluoroquinolone with resolution of symptoms. A follow-up chest CT scan 3 months later showed a small anterior right pneumothorax and improvement in right-sided effusion. The patient was asymptomatic at that time. The right sided pneumothorax continued to gradually increase in size on subsequent CT scans; however, he declined any workup given lack of symptoms. A few months prior to our evaluation, he started noticing gradually progressive exertional dyspnea and a nonproductive cough. He denied fevers, weight loss, chest pain, or hemoptysis. His past medical history was unremarkable except for glaucoma. He was a 75 pack year smoker who quit 3 years ago. He was exposed to asbestos while serving in the navy for 4 years and subsequently worked as a truck driver. All physical findings were normal except for decreased breath sounds in the anterior right lower chest on auscultation. Blood count and biochemistry were normal. Serial chest CT scans over a 1-year period show gradual enlargement of the right sided pneumothorax. (Figures 1, 2, 3, and 4). The patient was referred to thoracic surgery and underwent posterolateral thoracotomy. He was noted to have densely adherent right lower lobe that was dissected free from the posterior chest wall. There was a cyst-like sac in the region of the bronchus intermedius, which was opened to reveal a bronchopleural fistula. The cyst was removed and the fistula was closed. Pathology of the resected specimen was initially read out as exuberant mesothelial hyperplasia. Further review revealed