Preauricular Cyst Excision

Chapter Authors
Dr. Mai Thy Truong, MD, Clinical Associate Professor of Otolaryngology — Head & Neck Surgery (OHNS) and, by courtesy, of Pediatrics, Fellowship Director of Pediatric Otolaryngology

During embryogenesis, the pinna forms from six hillocks: three anterior and three posterior to the external auditory meatus. Preauricular pits result from errors in embryology. As the crus of the helix separates from the tragus, and the incisura deepens between the 1st and 2nd Hillocks of His, a pit can remain. The depth of the sinus varies from person to person. Some are shallow and cause neither drainage nor infection. If the sinus tract becomes obstructed, it may enlarge to form a cyst. These cysts typically adhere to the helical cartilage and sometimes penetrate it. Although commonly limited to the preauricular region, in rare cases tracts can dive either through or beneath the auricular cartilage and may present as a postauricular abscess. They may also be associated with a first branchial cleft fistula that continues parallel to the ear canal or descends deeply into the parotid and even into the upper neck.
Preauricular cysts are prone to recurrent infections. When they have been repeatedly infected, especially when they have been incised and drained, considerable scarring to adjacent tissues as well as the overlying skin may be present.
Growth pattern of preauricular cysts. Skin changes sometimes appear discontinuous to the pit.
Incision for excision of a small preauricular cyst. The scar aligns with the front edge of the helical crus. The extent of the cyst can sometimes be palpable, although if deflated after recent infection the extent may be difficult to discern. The size of the affected area in previous infections can also clue the surgeon to the approximate size of the cyst.
Incision for excision of a moderate sized preauricular cyst.
Incision for excision of a large preauricular cyst may align with the pretragal crease or be carried up onto to the tragal crest.
Excision of multiply infected, large preauricular cysts can present technical challenges. When the preauricular skin is abnormal due to recurrent infection and/or repeated drainage, the overlying skin should be removed together with the pit. In this situation, rather than try to follow the contours of the cyst, it is best to establish the plane on the temporalis fascia superiorly and dissect the infected cyst off the fascia en bloc with a cuff of surrounding scar tissue. The temporalis fascia, more specifically the superficial layer of the deep temporal fascia, continues inferior to the zygoma as parotid-masseteric fascia. So long as this fascial layer is not violated, the facial nerve is safe. Because the anterior margin of larger preauricular cysts may approach the temporal branch of the facial nerve, it is prudent to use electrophysiological monitoring. Closure of this wound is done with a face-lift technique. As the closure is often tight, undermining the facial skin may be needed to create the mobility to enable primary closure. Absolute hemostasis is required, especially as many branches from the superficial temporal artery are in this path.
The temporalis fascia, more specifically the superficial layer of the deep temporal fascia, continues inferior to the zygoma as parotid-masseteric fascia. So long as this fascial layer is not violated, the facial nerve is safe.
In large preauricular cysts, especially those that have been infected numerous times, dissection of the cyst with a surrounding cuff of tissue off the temporalis fascia is the best strategy for achieving total removal.
After an elliptical incision through the skin and dermis, dissection is first focused superiorly. The interface of the cyst with the helical cartilage is first identified and followed off the edge toward the temporalis fascia anteriorly. Once these superior borders of the cartilage and fascia are identified, the cyst is then circumferentially dissected.
Following the surface of the cyst, its attachment to the helical crus is defined. To decrease the risk of recurrence, the cartilage in contact with the cyst should be excised and removed with the cyst. The surface of the cartilage is exposed peripherally around the cyst, allowing for an elliptical incision on the cartilage. While removing cartilage, it is important not to violate the skin of the cymba concha which underlies it.
A freer elevator or scalpel can facilitate the removal of the cartilage from the undersurface of the skin of the cymba concha.
Some surgeons use a lacrimal probe and methylene blue dye to map out the extent of the cyst. The lacrimal probe is used first to gently dilate the opening to allow the introduction of methylene blue. If this is done aggressively, a false passage can be made, allowing the extravasation of methylene blue into normal tissues. Typically, lacrimal probes from size 0 up to no larger than size 1 are used. Methylene blue can often guide the dissection and allow reassurance of complete removal when the cyst is adequately dyed.
Methylene blue is injected with a 1-mL TB syringe via a 24-gauge Angiocath to allow for controlled introduction. The corner of an alcohol wipe can be kept at the opening to collect any excess methylene blue. Very little dye is often needed to stain the cyst, and a gentle tap of the syringe is recommended over a push.
Once the blue has dyed the cyst, the removal continues as in Fig. 3.157. If methylene blue seeps from the pit during the early dissection, it is merely suctioned away from the pit.
Once the ellipse has been cut and the cyst begins to be freed, the lacrimal probe can be reintroduced. The probe has dual purposes: to plug the pit to reduce extravasation of dye and also to palpate the extent of the cyst. A small Allis clamp secures the lacrimal probe while establishing traction while dissecting the cyst. Care must be taken to not rotate the Allis clamp along its axis as torsion may lead to a rupture of the cyst.

 

Dr. Jackler and Ms. Gralapp retain copyright for all of their original illustrations which appear in this online atlas.  We encourage use of our illustrations for educational purposes, but copyright permission should be sought before publication or commercial use. To request permission for publication or commercial use please contact Christine Gralapp (eyeart@chrisgralapp.com, https://www.chrisgralapp.com).