12.1 Goals

The goal of this procedure is to remove the lesion and to do so completely. To remove the lesion in its entirety, care is taken to keep the cyst wall intact throughout the procedure, with its contents contained within its capsule. Removal of the lesion completely avoids the possibility of further growth and future recurrences as well as postoperative orbital granulomatous inflammation (a sequela of ruptured contents described below). ^{1 , 2} Although removal of the lesion is the primary goal, a secondary goal of the procedure is to eliminate an often-noticeable deformity and to optimize and minimize the incision utilized for excision. Usually a segmental upper eyelid crease incision is utilized to access the lesion, although a sub-brow incision can also be used for much larger or more adherent lesions.

12.2 Advantages

Although dermoid cysts are benign lesions, the material contained within them can cause severe inflammation. This material is kept at bay by its natural encapsulation, but even mild trauma such as a bumped head or unintentional fall of a newly walking toddler can cause a rupture. As the content leaks or spills out into adjacent tissue, it can cause a significant granulomatous inflammation, often mimicking the appearance of periocular cellulitis. Additionally, uncontrolled rupture can disseminate contents subcutaneously, rendering future complete excision surgically challenging. To avoid the possibility of future inflammation and maximize the ease of complete excision, it is generally recommended to remove these choristomas at a relatively young age. Although there is no absolute age, standard of care is usually to remove them around the age of 1 year old—beyond the period of higher risk general anesthesia in infancy and before fully ambulatory and at greater risk of accidental trauma. By removing the lesion at a relatively young age, it also minimizes the size of the incision required for excision and eliminates future molding of surrounding tissues that can occur with untouched, chronic lesions.

12.3 Expectations

The expectation of dermoid excision is that the cyst is removed safely without complication or deformity.

12.4 Key Principles

Dermoid cysts are most frequently located in the superotemporal quadrant at the frontozygomatic suture line, ³ but can also occur at other suture lines including the superonasal frontoethmoidal suture line. Superficial dermoid cysts tend to present within the first year of life as a visible and/or palpable mass noted at the orbital rim. ¹ Deep dermoid cysts grow innocuously within the orbit and consequently present later in life (teen or adult years) with manifestations such as proptosis or globe dystopia. ¹ When approaching dermoid cyst excision, plan your approach and take it slowly. Utilize the most cosmetically favorable incision possible—often an upper eyelid crease incision. That being said, give yourself the access and exposure you need to successfully remove the lesion completely and do not compromise adequate exposure for a more cosmetically favorable incision. Without proper exposure, one risks intraoperative rupture which puts the patient at risk for recurrence and ongoing inflammation if not thoroughly debrided.

Use layer-by-layer dissection until the cyst is encountered and then dissect around the capsule with as much blunt dissection as possible and limited sharp dissection. Consider leaving a few fibers of tissue on the capsule to grasp for traction to avoid risking rupture by grasping the capsule itself. A cryotherapy probe can also be utilized and provides excellent traction without rupture when applied to the capsule.

Occasionally, the cystic cavity will extend through the lateral wall into the temporal fossa forming a “dumbbell”-shaped lesion. These lesions should be suspected preoperatively due to their immobility and confirmed with imaging. When excising this type of lesion, attempts should be made to eliminate components from the bony canal with a drill or bone curette and irrigation.