Abstract
BACKGROUND: Hydatid cyst is a parasitic infection caused by a tapeworm Echinococcus granulosus, mainly involving the liver and lungs with orbital involvement being very rare but when involved can result in unilateral proptosis leading to vision loss in chronic cases. Here, we present a rare case of unilateral orbital hydatid cyst in young male patient of pediatric age group which was successfully treated. CASE REPORT: A four years old male patient presented with history of trauma and unilateral painless temporal proptosis with dystopia of right eye for two months. On ocular examination, his visual acuity in the right eye was 6/60 and in the left eye it was 6/6. In his right eye there was a positive Relative Afferent Pupillary Defect. On fundus examination, the optic disc was swollen in right eye. The dystopia was 10 mm each, laterally and inferiorly, there was also resistance to retropulsion. In the right eye extraocular movements were restricted in all gazes, a soft tender mass was palpable superior-medially and mild lagophthalmos was also present. Magnetic resonance imaging findings led to the diagnosis of orbital hydatid cyst being the cause of proptosis. Surgical removal of the cyst through superior orbitotomy was performed and its contents were aspirated under general anesthesia. The diagnosis of orbital hydatid cyst was confirmed by histopathological reports of the cyst walls and the aspirated fluid. CONCLUSION: Orbital hydatid cyst is a very rare occurrence and should be considered a differential diagnosis of proptosis in pediatric population. Surgical removal of the cyst is the main treatment option followed by oral Albendazole for three months.