Incidental cytodiagnosis of microfilaria from subcutaneous nodule

A 35-year-old woman presented with a swelling of the right forearm to the surgery outpatient department at the All India Institute of Medical Sciences, Raipur. On examination, she had a subcutaneous swelling in the right forearm, painful and diffuse measuring 3× 3 cm for 6 months [Figure - 1]A. A fine-needle aspiration was done and the material was sent for cytological examination with a clinical impression of fibro-lipoma. Blood mixed fluid was aspirated and routine Giemsa and Pap stains were done. Cytological examination revealed epithelioid granulomas with lymphocytes and microfilariae in a haemorrhagic background [Figure - 1]B, [Figure - 1]C, [Figure - 1]D. The microfilaria was sheathed and the column of nuclei in them with the tail tip being free [Figure - 1]E, [Figure - 1]F. A cytological diagnosis of granulomatous inflammation due to microfilaria morphologically consistent with Wuchereria bancrofti was made. She was treated with diethylcarbamazine (DEC) for 3 weeks. On follow-up, the swelling subsided.

Figure 1: Swelling in the right forearm of the patient Figs1B, C, D, E, F. Cytosmears showing microfilariae (star) in a granulomatous inflammatory (arrow) background comprised foreign body-type giant cells and histiocytes (Giemsa × 400; PAP, × 400)

Even in the absence of clinical indications and eosinophilia in peripheral smears, microfilaria can be detected in subcutaneous nodules. Hence, careful screening for microfilariae is important in aspiration cytology smears.