Microfilariae in thyroid aspiration smear--an unexpected finding.

Lymphatic filariasis is a major health problem in tropical countries including India. Despite its high incidence it is difficult to find microfilariae in blood and fine-needle aspirates due to the nocturnal periodicity of species endemic in India. Lymphatic filariasis can manifest as asymptomatic microfilaremia, hydrocele, lymphangitis, and lymphadenitis. The presence of microfilariae in thyroid aspirates is a rare finding. A case of microfilariae in a thyroid aspirate is being reported to emphasize the significance of careful screening of smears in endemic areas.