Isolated hydatid cyst in the medial rectus muscle: unveiling a rare orbital occurrence.

Background: Orbital hydatid disease, while rare, should be included in the differential diagnosis of unilateral proptosis, particularly in endemic areas. Accurate diagnosis and comprehensive management are essential for effective treatment and favorable long-term outcomes.

Case presentation: A 12-year-old boy presented with a one-month history of diplopia and left-sided proptosis. A CT scan revealed a cystic mass within the left medial rectus muscle. Surgical intervention confirmed the presence of a hydatid cyst following cyst rupture and irrigation with hypertonic saline. The patient underwent a two-month course of albendazole therapy. Initially, the patient experienced persistent exotropia and diplopia, but at the three-year follow-up, he exhibited no diplopia or proptosis and only mild residual exotropia.

Conclusion: This case underscores the importance of considering orbital hydatid cysts in the differential diagnosis of unilateral proptosis in endemic regions. Heightened awareness, accurate diagnosis, and a tailored therapeutic approach, including surgical removal and antiparasitic treatment, are crucial for successful management and improved long-term outcomes.