Human pulmonary dirofilariasis in Taiwan

Pulmonary dirofilariasis is a rare zoonotic disease in the United States. Most reported cases were from the southeastern or Gulf states. The disease is caused by Dirofilaria immitis (dog heartworm), a filarial nematode, and is transmitted to humans by mosquitoes. A 69-year-old asymptomatic man was found to have a pulmonary nodular lesion on chest x-ray during routine health examination. The lesion was resected, and pulmonary dirofilariasis was diagnosed based on histological findings. Postoperatively, recovery was uneventful. This is the second reported case of human pulmonary dirofilariasis in Taiwan. Awareness of this entity is important, since the clinicoradiographic presentation of human pulmonary dirofilariasis may mimic lung neoplasia. This case may help alert clinicians, radiologists, or pathologists that pulmonary dirofilariasis should be included in the differential diagnosis when a subpleural 'coin-like' lesion is observed on chest x-ray.