[An unusual cause of the hand cyst: finger dirofilariasis].

Dirofilariasis is a zoonosis affecting dogs and cats. It can be transmitted to human by mosquito bites. Because of the local inflammation caused by the parasite, a lump may develop. The authors present a case of a 13-year-old boy, who was diagnosed with dirofilariasis in association with a cyst located on the middle finger of the right hand. During physical examination, a lump on the extensor surface of the middle phalanx of the right middle finger was found. Soft tissue ultrasound was performed, which indicated the presence of a worm in the cyst. The cyst was surgically removed under local anesthesia and with parasitology test Dirofilaria repens infection was confirmed. The child had no complains or symptoms during recovery after the surgery. A solitary growth developing on the fingers of the hand often presents a differential diagnostic problem. Ultrasound can be greatly helpful in the preoperative diagnosis. Orv. Hetil., 2016, 157(39), 1571-1574.