Role of fine needle aspiration cytology in detection of microfilariae - Report of 2 cases

Background Filariasis is a major public health problem in developing countries, and the diagnosis is conventionally made by demonstrating microfilariae in the peripheral blood smear. However, microfilariae have been incidentally detected in fine needle aspirates of various lesions in clinically unsuspected cases of filariasis with absence of microfilariae in the peripheral blood. Cases In case 1, a 21-year old woman presented with multiple left axillary lymphadenopathy of 3 months' duration. In case 2, a 32-year old woman presented with a thyroid nodule of 7 months' duration. Fine needle aspiration smears from both cases showed sheathed microfilariae of Wuchereria bancrofti. In both cases, microfilariae could not be demonstrated in the peripheral blood smears and the blood eosinophil counts were within normal limits. The histopathologic examination showed neither microfilariae nor adult worm. Conclusion Although microfilariae in cytologic material are considered , incidental findings, these cases illustrate the value of routine fine needle aspiration cytology in the detection of asymptomatic and clinically unsuspected cases of bancroftian filariasis. Absence of microfilariae in, the peripheral blood does not exclude filarial infection.