Human dirofilariasis - an unusual mode of presentation at fine needle aspiration

Human dirofilariasis due to Dirofilaria (Nochtiella) repens has been reported from many parts of Europe, Asia, and Africa. Detection of this nematode in subcutaneous tissue in man (an abnormal host) at histology has been well documented. We report the detection of a dead and degenerate adult female Dirofilaria repens at the fine needle aspiration puncture site of a subcutaneous lesion. A 21-year-old girl was referred for fine needle aspiration biopsy (FNAB) of a localized swelling of the right forearm, measuring 4 x 3 cms. Fine needle aspiration was performed by the classical aspiration technique using 23 gauge needle. As the needle was withdrawn from the lesion following the aspiration, a fine, white, thread-like structure was seen protruding from the puncture site. It was identified as an adult female of the nematode species Dirofilaria (Nochtiella) repens with a length of 80.5 mm and a maximum width of 450 um. FNAB is a standard diagnostic technique performed on palpable lesions of many sites, including subcutaneous nodules. As most human dirofilariasis present in the form of subcutaneous nodules, awareness of this phenomenon will be useful not to miss the detection of the parasite in this interesting and unusual mode of presentation.