Periorbital dirofilariasis—Clinical and imaging findings: Live worm on ultrasound
A 2-year-old female child presented with acute onset of periorbital edema in right eye. She was initially diagnosed as preseptal cellulitis and treated with systemic antibiotics. There was mild resolution of edema, but a cystic swelling was apparent in the right upper eyelid.\nUltrasound was performed with high-resolution probe (8MHz) and showed a well-defined cyst approximately 2.5×1.5 cm in the lateral part of right upper eyelid. The cyst showed within it a coiled structure with parallel echogenic walls []. It showed continuous movement which represents the live worm. MRI was done to know any deep intraorbital extension and exclude other intraorbital abnormalities. MRI of orbits showed a cyst in the lateral part of upper eyelid which showed hyperintense signal on coronal short-tau inversion recovery image [], hypointense signal on coronal T1 image [] and revealed rim enhancement on post-contrast T1-weighted fat saturated images [ (coronal) and (sagittal)]. The cyst was confined to the upper lid. Ill-defined intermediate signal intensity was seen on STIR images [] within the cyst which may represent the worm.\nSurgical excision of the parasitic cyst was done through an upper lid crease incision. The cyst was adherent to the levator palpebrae superioris muscle. It contained a live motile worm measuring about 9 cm in length []. Histopathological examination [] showed a worm with thick cuticle, muscle coat, longitudinal and transverse striations and double uterus. Based on histopathological appearance, the worm was identified as D.repens.\nPost-operatively, the child was asymptomatic except for a mild residual ptosis which was improving.