Periorbital dirofilariasis.

A differential diagnosis of inflammatory periocular soft tissue masses includes sarcoidosis, ruptured dermoid cyst, infectious abscess, metastatic neoplastic disease, and idiopathic pseudotumor. The authors present the case of a 42-year-old woman with a periocular inflammatory mass caused by dirofilaria of a nematode classification as Dirofilaria tenuis. The extraction of the worm was curative and the patient has been symptom-free for the ensuing 12 months. This zoonotic infection, spread by mosquito vectors from animal hosts to humans, is rarely encountered in the United States as a cause of periorbital inflammation. A history of migratory swelling and residence in, or travel to, endemic areas (the southeastern United States) should suggest the possibility of Dirofilaria infection.