Lateral rectus dermoid cyst presenting as incomitant esotropia

Area of Science:

• Ophthalmology
• Pathology

Background:

• Orbital dermoid cysts are typically superficial lesions, often found near suture lines.
• Intraorbital dermoid cysts, especially those within extraocular muscles, are uncommon.

Observation:

• A 24-year-old male presented with decreased vision, esotropia, and proptosis of the left eye.
• Ocular examination revealed reduced visual acuity (2/60), restricted abduction, and medial dystopia.
• Computed tomography (CT) identified a well-circumscribed mass adjacent to the optic nerve, mimicking the lateral rectus muscle.

Findings:

• Intraoperative findings confirmed a well-encapsulated mass within the left lateral rectus muscle.
• Histopathological analysis identified the mass as a dermoid cyst.
• The patient underwent successful surgical correction for esotropia.

Implications:

• This case highlights that deep dermoid cysts can occur within extraocular muscles.
• Dermoid cysts should be considered in the differential diagnosis of focal extraocular muscle enlargement.
• Prompt diagnosis and surgical intervention can yield favorable cosmetic and functional results.