Periorbital subcutaneous tumor-like lesion due to Dirofilaria repens

Dirofilariasis is a zoonotic infection, which is occasionally seen in humans and rarely found as a subcutaneous orbital swelling. The authors report a case of a 62-year-old woman presented with a 3-month history of a right periorbital subcutaneous nodule. Treatment with antibiotics and corticosteroids was not satisfactory. Magnetic resonance imaging analysis showed a nodule with a central colliquative area. The lesion displaced the eyeball superiorly but did not affect the intraorbital muscles. The patient was subjected to excisional biopsy and the nodule measured 15 mm. Histological findings showed microabscess reaction with heterogeneous lymphoid infiltration. Additional consecutive sections finally showed Dirofilaria repens, curled up in spirals with external cuticular ridges in an environment characterized by epithelioid cells. The lesion did not recur for 5 months. Periorbital swelling can be rarely caused by Dirofilaria repens; therefore, this diagnosis should be considered in all cases of subcutaneous inflammatory or tumor-like lesion of unknown etiology.