Fibrous subcutaneous nodule caused by Dirofilaria repens.

A case is described of subcutaneous dirofilariasis in a Greek woman who had visited many countries around the world, including areas of sub-Saharan Africa. The patient presented with a single hard subcutaneous nodule on the right cheek, with no cutaneous manifestations of early or long-standing onchocercal dermatitis or eye lesions. The nodule was removed surgically and the filarial adult worm Onchocerca volvulus was initially diagnosed, based on the history, the hardness and large size of the fibrous nodule and the absence of cuticular longitudinal ridges of the parasite in the initial histological sections. Bloodless skin snips taken from the regions of the scapula, iliac crest and lateral calf were negative for O. volvulus microfilariae. Serial cross-sections of the fibrous nodule and gross examination of a portion of the adult worm removed from the nodule revealed the characteristic longitudinal ridges which allowed the identification of the worm as Dirofilaria repens. The aim of this report on tropical and non-tropical filarial worms affecting the skin and eyes is to point out the key features for precise identification of the parasites and differential diagnosis of the infections caused by the filiform nematode worms of O. volvulus, and Dirofilaria species.