Filarial Worm Infestation of the Nasolacrimal Duct: A Rare Orbital Presentation.

Filarial infestation of the nasolacrimal duct is exceptionally rare and often misdiagnosed as benign lacrimal pathology. We present a 12-year-old boy with progressive medial canthal swelling initially suspected to be a dermoid cyst or inflammatory lesion. Magnetic resonance imaging revealed a well-defined enhancing lesion at the nasolacrimal duct with preseptal edema. Histopathology demonstrated a parasite with a thick eosinophilic cuticular wall and inflammatory infiltrate rich in eosinophils and foreign-body giant cells, consistent with filarial infestation, possibly Onchocerca species. Surgical excision followed by antifilarial therapy resulted in complete recovery without recurrence at 3-month follow-up. Heightened clinical awareness in endemic regions is essential to enable timely diagnosis and effective management.