Cytomorphology of filariasis revisited: Expansion of the morphologic spectrum and coexistence with other lesions

To review the cytomorphologic spectrum of the filarial worm and associated tissue response in 33 cases. Retrospective analysis was carried out in clinically unsuspected cases of filariasis diagnosed on cytology over a period of 10 years. Twenty-nine aspirate smears from 28 patients were air dried and stained with May-Grünwald-Giemsa stain. Four routine cervical smears and one centrifuged smear of urine were stained with Papanicolaou stain. Microfilariae alone and along with adult gravid females were present in 25 and 4 cases, respectively. In one case both adult male and female worms with microfilariae and eggs were seen. The diagnosis was based on the presence of eggs alone in one case and fragments of female worms in two. Four of these cases were neoplastic lesions, and microfilariae were found incidentally. In one case of splenomegaly microfilariae were seen along with Leishman-Donovan bodies. Filariasis can be diagnosed on cytology by demonstrating microfilariae, a male or female worm, or eggs alone. It can be seen in association with neoplastic lesions and rarely with other parasitic infections.