Pleuropulmonary paragonimiasis with intrathoracic mass

Pleuropulmonary paragonimiasis is a food-borne parasitic disease caused by the lung fluke Paragonimus westermani or other species of Paragonimus, which is endemic in Southeast Asia. It presents mainly pleural effusion or intrapulmonary nodules with respiratory symptoms. However, here we describe an exceedingly rare case of Paragonimus westermani with a mass in the pleural cavity. A 47-year-old man, who had presented with chest pain nine months earlier, was found to have right pleural effusion on detection survey computed tomography. He had a history of asbestos exposure and river fishing as a hobby and was confirmed to have Paragonimus westermani by immunodiagnosis. Because of a high level of hyaluronic acid in pleural effusion, he underwent a thoracoscopic examination. The pleura of the thoracic wall thickened greatly and showed no malignant lesion on biopsy. A white mass measuring 8 cm in diameter showed in the pleural cavity, which partially connected with the diaphragm and pulmonary pleura of the lower lobe. The postoperative pathological examination reported that the intrathoracic mass was a lesion that contained necrotic tissue enveloped with a fibrin capsule, which was thought to be formed by paragonimus.