Parasitic infections of the pleural space.

Parasitic infections are a sufficiently common cause of pleural disease that parasitosis should be considered in any effusion of unclear cause. They can involve the pleura with or without involvement of the adjacent lung. Amebiasis affects the pleural by crossing the diaphragm from a liver abscess. This is particularly important to diagnose because of the ease of treatment and the severe course of the untreated disease; the gross appearance of the pus may be diagnostic. Cystic hydatid disease can be primarily pleural, but more often reaches the pleura by rupture of a cyst in the lung or liver. Rupture often calls for aggressive surgical treatment; it may be complicated immediately by anaphylaxis, earlier by empyema or lung abscess, and later by secondary disseminated hydatidosis. Pleural paragonimiasis is often mistaken for tuberculosis. Patients are not likely to have diagnostic eggs in the sputum or stool, but the pleural fluid is characteristic. Other parasitic infections that have rarely been associated with pleural disease include pneumocystosis, Loeffler's syndrome, tropical pulmonary eosinophilia, toxocariasis, anisakiasis, hypodermiasis, strongyloidiasis, and schistosomiasis. Some parasites, including pentastomids and Mansonella sp, can be found in the pleura incidentally by radiograph or autopsy, but seldom if ever cause pleural disease.