Epidermal dermoid cysts are believed to develop from epidermal rest cells that get entrapped in the deeper tissues during embryonic development. This explains their tendency to occur in the orbit at sites of bony fusion, particularly along the zygomaticofrontal suture. Their natural history is of a gradually enlarging cystic mass with displacement of adjacent structures, although some may remain relatively dormant[4, 11]. Spontaneous or traumatic rupture of the cyst occasionally occurs, resulting in inflammation and a rapid increase in the size of the lesion.
Microscopic examination of such lesions reveals chronic granulomatous inflammation in the epithelial wall. These epithelioid and foreign body giant cells were, however, absent in our case. Thus, small asymptomatic orbital dermoid cysts may not require any immediate treatment, as they can remain stable for years or reduce in size. However, deeper seated lesions frequently present later in life as giant dermoid cysts that require excision, and may present a surgical challenge[2, 4, 8]. Similar to previous reports[8, 12], the cystic mass was located in the superotemporal quadrant portion of the orbit, but with extension into the posterior orbit in our patient. Sherman and associates reported on five patients with deep orbital dermoid cysts, aged 15 to 40 years. All presented with normal visual acuity and ocular motility and subsequently had simple tumor excision. A similar case was described by Bickler-Bluth et al.. One of the patients in the series by Shields and associates presented with a giant orbital cyst at birth, similar to our case, but with well preserved ocular anatomy. Early presentation and surgical intervention has been advocated as the key to a good outcome in this group of patients.
Late presentation has affected the management of many benign ophthalmic conditions in developing countries, and it is not unusual for the parents to have tried other remedies before finally presenting to the hospital or agreeing with the treatment offered. Superstitious beliefs and financial constraints were identified as reasons for patients in our environment presenting late to the eye-care facilities, with consequent poor outcome in management. Our patient initially presented at three months of age when the cornea was already hazy, subsequently defaulted from the surgical treatment offered, and re-presented after two years with large proptosis, a massively expanded orbit, lagophthalmos, and a keratinized ocular surface from exposure keratopathy. At this time, the best surgical intervention we could offer was lid-sparing exenteration. Simple tumor excision could have been done if the parents had presented our patient earlier, sparing the globe and, possibly, providing a good visual prognosis.