Incidental Diagnosis of Filariasis in Superficial Location by FNAC: A Retrospective Study of 10 Years

Background: Filariasis, transmitted by the bite of various species of mosquito, is a common disease of tropical belt of the world. In South East Asia, including India, it is a major public health problem. The parasite is primarily confined to Lymphatic channel or lymph nodes where it can remain viable for more than two decades. The most common presentation of the disease is asymptomatic/ subclinical microfilaremia, Hydrocele, acute adeno-lymphangitis (ADL) and chronic lymphatic disease. However, the disease may rarely present as superficial swellings at unusual sites. Incidental findings of microfilaria on fine needle aspiration cytology in these situations, helps in prompt recognition of the disease.

Aim: The aim of this retrospective study was to assess the incidental diagnosis of Filariasis on fine needle aspiration cytology (FNAC), done for swellings in superficial locations over last ten years at our institute.

Materials and methods: This retrospective study was conducted over a period of 10 years from April 2003 to March 2013 on the cases where FNAC was carried out on swellings in superficial locations of the body. Twenty cases of filariasis were diagnosed on routine FNAC material obtained from various superficial sites. Their data was retrieved and analyzed.

Results: Among the 20 cases diagnosed as filariasis on FNAC, six cases involved lymph nodes, six involved testiculo-scrotal region, three cases of thyroid swelling, soft tissue swelling in three cases and breast lump in two cases. On FNA smears, microfilariae were seen in all 20 cases, eggs in three cases, adult female worm in two cases and adult male worm in one case. Adherence of inflammatory cells and macrophages to microfilariae was noticed in 4 cases. Eosinophilia was present in seven cases. Microfilaremia was present in only three cases. Causative agent was Wuchereria bancrofti in all cases.

Conclusion: Although not so common, filariasis should be considered as one of the differential diagnosis of a superficial swelling particularly if clear fluid is obtained on FNAC. Careful screening of smears plays a significant role in recognition of the disease even in asymptomatic patients.