Pulmonary dirofilariasis

Background. Pulmonary dirofilariasis is a rare entity caused by Dirofilaria immitis, the dog heartworm that is transmitted to humans by mosquitos. This filarial nematode enters the subcutaneous tissue, travels to the right ventricle where it dies, and then embolizes the pulmonary vasculature, causing a small pulmonary infarction, which subsequently appears as a solitary nodule. Although these nodules are usually identified incidentally by chest radiography in asymptomatic patients, the lesion is generally presumed to be neoplastic. Diagnosis is made by surgical excision. Methods. We reviewed the pathology reports at Memorial Medical Center, Savannah, GA since 1990. Results. There have been approximately 150 cases reported in the literature worldwide. We found 4 patients with pulmonary dirofilariasis diagnosed at our hospital since 1992. A review of the pathogenesis of the disease and clinical manifestations, diagnosis, and treatment of this entity are presented. Conclusions. Pulmonary dirofilariasis is a benign condition, transmitted by mosquitos to humans that results in peripheral pulmonary nodules. Awareness of this entity is important in the differential diagnosis of pulmonary coin lesions.