Role of Cytology in the Diagnosis of Atypically Presenting Filariasis: Evaluation of a Tertiary Care Hospital Experience

Background: Filariasis is a global health problem. Lymphatic filariasis is India’s second most common vectorborne disease and a major contributor to chronic deformities like elephantiasis. The disease is widespread in India, and highly endemic zones are present in several states, particularly Chhattisgarh, Uttar Pradesh, Bihar, Orissa, Jharkhand and Andhra Pradesh. Filariasis can rarely present as asymptomatic swellings in various unusual sites in the body and very uncommonly as a sole finding in effusion cytology. Therefore, cytology plays a crucial role in the incidental diagnosis of filariasis in clinically unsuspected cases. This study aims to analyze cytology’s role in diagnosing filariasis, especially in clinically unsuspected cases, and to study the cytological findings associated with filariasis in these cases. Materials and Methods: This study was conducted in Chhattisgarh Institute of Medical Sciences, Bilaspur. The records from the department of cytology Chhattisgarh Institute of Medical Sciences were searched from January 2022 to Dec 2025. We collected the cases for this study from our routine cytology cases (FNAC/Body fluids) over four years. Two pathologists then evaluated all the diagnosed cases of filariasis in cytology. Descriptive statistical analysis was done wherever required. In four-year study period we found eight cases of filariasis in routine cytology smears (FNAC/Body fluids). Results: Out of these eight cases, one case each from breast and thyroid swelling, three cases were diagnosed in cytology smears from subcutaneous swellings, one from axillary lymph node and two cases were diagnosed in fluid cytology. All these cases had incidental findings of microfilariasis varying from one-to-many parasites per slide on cytological examination. In none of these cases, filariasis was suspected by the clinicians. Conclusion: Cytology plays a crucial role in diagnosing filariasis in endemic areas, especially in those with atypical presentations. Therefore, meticulous screening of all cytology smears is strongly indicated.