[Two resected cases of human pulmonary dirofilariasis]

Two patients with human pulmonary dirofilariasis are presented. A 58-year-old woman in Tokyo (Case 1) was pointed out to have a nodular shadow in the right lower field on a routine chest X-ray in 1983. At thoracotomy a 2 cm nodule in the right lower lobe was removed by wedge resection. The nodule was a granuloma containing an immature Dirofilaria species. A 49-year-old man living in Chiba Prefecture (Case 2) was found to have a nodular shadow in the right lower lobe on a chest X-ray in 1987. He was asymptomatic, but laboratory values showed a WBC count of 5,800 with 17% eosinophils. Wedge resection of the lesion was carried out and it was found to be a 2 cm granuloma containing an immature Dirofilaria immitis. The dog heartworm, D. immitis, can occasionally cause pulmonary granulomas in man. More than 50 cases have been reported in Japan, but most of them were diagnosed by postoperative histopathologic examination. Although immunoserological examination or medical treatment were attempted in some cases, they are not established at present. The important thing is that pulmonary dirofilariasis should be included in the differential diagnoses of nodular lesion of the lung.