Filarial dance sign in a subcutaneous thigh swelling: Diagnosis by high-resolution ultrasonography and aspiration cytology

Subcutaneous filariasis is an uncommon manifestation of lymphatic filariasis, which remains a major parasitic disease in tropical and subtropical regions, particularly in India. Although the disease classically presents with lymphatic obstruction, hydrocoele, lymphoedema, and elephantiasis, localised subcutaneous filariasis is uncommon and may clinically resemble a benign soft-tissue lesion. High-resolution ultrasonography can facilitate diagnosis by demonstrating the characteristic ‘filarial dance sign’, representing motile filarial worms within dilated lymphatic channels.