Facial subcutaneous filariasis on ultrasonography imaging - An uncommon finding

Filariasis, a major public health concern in endemic regions, typically manifests with lymphatic involvement. However, extralymphatic presentations, such as subcutaneous nodules, are rare. This case report describes two unusual instances of facial subcutaneous filariasis in patients from Maharashtra, India. A 46-year-old male presented with a painless right cheek swelling, while a 50-year-old female had a similar lesion in the left cheek. High-resolution ultrasonography (USG) revealed cystic lesions with echogenic tubular structures, demonstrating the pathognomonic “filarial dance sign” (FDS) in the first case, indicative of live microfilariae. Both patients underwent surgical excision, with histopathology confirming adult filarial worms ( Wuchereria bancrofti and Dirofilaria spp.) surrounded by eosinophilic infiltrates and granulomatous inflammation. These cases highlight the diagnostic utility of USG in detecting extralymphatic filariasis and underscore the importance of considering filarial infestation in subcutaneous nodules, even in non-endemic urban settings. Early recognition and treatment with antiparasitic therapy or surgical intervention can prevent complications.