Significance of incidental detection of filariasis on aspiration smears: a case series.

Filariasis is a major public health problem in tropical and subtropical countries including India. Although there are reports of incidentally diagnosed cases of lymphatic filariasis in the existing literature, the significance of this finding needs to be summarised in one place. The association of filariasis with neoplasms is still debatable. For this series, cases diagnosed as filariasis on aspiration cytology (with or without coexistent pathology) over a period of 1 year were retrieved. The cases with a clinical suspicion of filariasis were excluded. Hence, five cases with incidental diagnosis of filariasis on aspiration cytology were included. The site of aspiration included one case each of thyroid, breast, bone marrow, cervical lymph node, and subcutaneous nodule. Of these, three cases showed microfilariae, one showed only adult female worm while one showed both microfilariae and adult worm. Two cases did not show any inflammatory response while three cases showed a variable inflammatory reaction. Only one case (thyroid aspirate) had a coexistent pathology (colloid goitre). Filariasis may be detected in a clinically unsuspected case, especially in an endemic zone. The spectrum of host response may vary from no reaction to a marked inflammatory response. The entire spectrum of changes should be kept in mind while practicing cytopathology in an endemic area. In such situations, a high index of suspicion and careful screening of cytology smears are keys to a correct diagnosis. At the same time, keen search for a coexisting pathology, benign or malignant, is also mandatory.