Dirofilaria immitis (dog heartworm) as a pulmonary lesion in humans

Dirofilaria immitis, the dog heartworm, has been identified in the pulmonary granulomas of 5 patients from the greater Charleston area; this is the largest series of such cases from one medical center. The patients had no pulmonary symptoms. On roentgenogram the lesions were all about 2 cm in size, of uniform light opacity, and located near the pleural surface. Thoractomy was performed in each instance because of the possiblity of carcinoma. The association of granuloma formation, pulmonary infarct, and eosinophilic infiltration led to the suspicion of dirofilaria, which was confirmed in each case.