Orbital dermoid mimicking a monocular elevation deficiency.

Dermoid cysts are choristomas (a mass of histologically normal tissue in an abnormal location), which originate from aberrant primordial tissue and are often evident soon after birth. It may occur anywhere in the body. Dermoid cysts account for about 3-9% of all orbital masses and 0.04-0.6% of primary orbital tumors. The frequent site of origin is the superotemporal quadrant of orbit. Depending on the location, size, and associated abnormalities of the cyst, the patient may have proptosis, diplopia, and restriction of eye movements. Monocular elevation deficiency (MED) is the inability to elevate one eye in abduction, adduction, or from primary position. We report this case of orbital dermoid in an adult female presenting as a monocular elevation deficiency with unilateral ptosis of right eye which was investigated and managed with good results.