Coexistence of microfilariae with follicular variant of papillary thyroid carcinoma: A rare case report

Abstract Filariasis is an infectious disease caused by various parasitic roundworms and remains a significant global health issue, especially in tropical regions such as India. The disease primarily affects the lymphatic system, commonly impacting the lower limbs, retroperitoneal tissues, spermatic cord, and epididymis. Here, we present a rare case in which microfilariae coexist with a follicular variant of papillary carcinoma in the right thyroid lobe of a young female. Microfilariae were incidentally detected on fine-needle aspiration cytology and confirmed by quantitative buffy coat examination. The patient was treated with diethylcarbamazine followed by definitive surgical management for thyroid carcinoma. This case highlights the importance of keeping a high index of suspicion for filariasis in endemic regions, even in cystic or neoplastic thyroid lesions, and emphasizes the role of cytology in diagnosis.