Dirofilaria repens diagnosed by the presence of microfilariae in fine needle aspirates: a case report.

Dirofilariasis due to Dirofilaria repens with viable microfilariae outside the worm have not been reported before. A 40-year-old truck driver from rural Shiraz, Iran, had a firm mass, 2.5 x 2.5 cm, at the dorsolateral aspect of the right forearm. Fine needle aspiration (FNA) was performed on 2 occasions. Several microfilariae with blunt heads, pointed posterior ends and empty caudal spaces resembling microfilariae of Wuchereria bancrofti but longer were seen. Since Iran is a nonendemic area for lymphatic filariae and the patient had a history of contact with a dog, with the impression of dirofilariasis, the mass was excised, and the presence of adult worms in tissue sections confirmed the diagnosis. This case ofsubcutaneous dirofilariasis was diagnosed by detecting microfilariae in FNA smears and was confirmed on histopathology.