Preauricular sinuses are common congenital malformations first described by Heusinger in 1864. Preauricular sinuses are frequently noted on routine physical examination as small dells adjacent to the external ear, usually at the anterior margin of the ascending limb of the helix. However, preauricular sinuses have been reported to occur along the lateral surface of the helicine crus and the superior posterior margin of the helix, the tragus, or the lobule. Anatomically, preauricular sinuses are lateral and superior to the facial nerve and the parotid gland.
Preauricular sinuses are inherited in an incomplete autosomal dominant pattern, with reduced penetrance and variable power of expression. They can arise spontaneously. The sinus may be bilateral in 25-50% of cases, and bilateral sinuses are more likely to be hereditary. In unilateral cases, the left side is more commonly affected.
Also see the related article Preauricular Cysts, Pits, and Fissures.
During embryogenesis, the auricle arises from the first and second branchial arches during the sixth week of gestation. Branchial arches are mesodermal structures covered by ectoderm and lined with endoderm. These arches are separated from each other by ectodermal branchial clefts externally and by endodermal pharyngeal pouches internally. The first and second branchial arches each give rise to 3 hillocks; these structures are called the hillocks of His. Three hillocks arise from the caudal border of the first branchial arch, and 3 arise from the cephalic border of the second branchial arch. These hillocks should unite during the next few weeks of embryogenesis. Preauricular sinuses are thought to occur as a result of incomplete fusion of these hillocks.
Preauricular sinuses are usually narrow, they vary in length (usually they are short), and their orifices are usually minute. They may arborize and follow a tortuous course in the immediate vicinity of the external ear. The preauricular sinuses are usually found lateral, superior, and posterior to the facial nerve and the parotid gland. In almost all cases, the duct connects to the perichondrium of the auricular cartilage. They can extend into the parotid gland.
In one study, the incidence of preauricular sinuses in the United States is estimated to be 0-0.9% and the incidence in New York State is estimated to be 0.23%.
In Taiwan, the incidence of preauricular sinuses is estimated to be 1.6-2.5%; in Scotland, 0.06%; and in Hungary, 0.47%. In some parts of Asia and Africa, the incidence of preauricular sinuses is estimated to be 4-10%. One study in Kenya found preauricular sinuses to be the most common congenital oral and craniofacial anomalies, with a rate of 4.3 cases per 1000 persons.
Preauricular sinuses have no associated mortality.
Morbidity associated with preauricular sinuses includes recurrent infections at the site, ulceration, scarring, pyoderma, and facial cellulitis. Specifically, the following conditions may occur: abscesses at and anterior to the involved ear, chronic and recurrent drainage from sinus orifices, malar ulceration, otitis externa, and unilateral facial cellulitis.
Surgical treatment has its own associated morbidity, with the possibility of postoperative recurrence.
The incidence of preauricular sinuses in whites is 0.0-0.6%, and the incidence of preauricular sinuses in African Americans and Asians is 1-10%.
Both men and women are affected equally by preauricular sinuses.
Preauricular sinuses arise in the antenatal period and are usually present at birth, but they can become apparent later in life.
Most people with preauricular sinuses are asymptomatic. Only one third of persons are aware of their malformations. In one study of 31 patients, once the lesions became apparent, about 9.2 years (on average) passed before they sought medical care.
Some patients with preauricular sinuses present with chronic intermittent drainage of purulent material from the opening. Draining sinuses are prone to infection. Once infected, these sinuses rarely remain asymptomatic, often developing recurrent acute exacerbations.
Patients with preauricular sinuses may present with facial cellulitis or ulcerations located anterior to the ear. These ulcerations are often treated without recognition of the primary source, and the preauricular sinus remains unnoticed.
Subsequent to infection, a patient with preauricular sinuses may develop scarring and disfigurement.
Infants of diabetic mothers are at increased risk for the oculo-auriculo-vertebral sequence, which includes sinuses.
The preauricular sinus usually presents as a small dell adjacent to the anterior margin of the ascending limb of the helix, as noted in the image below.
Small dell adjacent to the ear demonstrates the preauricular sinus.
Unless they are actively infected or have previously been infected with subsequent scarring, they are only small openings in the external ear. If associated conditions are present, one might see external ear anomalies, such as flop ears. Physical examination may reveal associated branchiogenic fistulas and/or hearing loss.
In 2006, Saltzmann and Lissner reported an unusual case of familial punctal atresia with apparent genetic linkage to bilateral preauricular sinuses that lacked any comorbid syndromic features, which is usually not the case.
Choi et al, in 2007, noted that what is termed the preauricular sinus can occur in the postauricular area. Sinuses occurring in the postauricular areas seem to have a lower rate of recurrence after surgery (0%) than those in the preauricular area (2.2%).
Associated conditions are as follows:
Associated facial pathology is as follows:
A novel autosomal dominant syndrome consisting of hypertelorism, punctal pits, preauricular sinus, and deafness (HPPD) located on 14q31 has been noted.
Other constellations of conditions that occur with preauricular sinuses include natal teeth, kidney stones, and atopic dermatitis.
Preauricular sinuses are malformations that result from incomplete fusion of 2 of the 6 hillocks that arise from the first and second branchial arches.
If exudate from the sinus is present, culturing should be performed so that antibiotic therapy tailored to the offending pathogen can be instituted. In 2002, Martin-Granizo et al suggested that initial fistula probing serves as a surgical guide and further methylene blue infection helps to avoid leaving viable squamous epithelial remnants.
Ultrasonography readily depicts preauricular sinuses and demonstrates their relationship to the superficial temporal artery, the anterior crus of the helix, and the tragus.
Upon gross examination, the preauricular sinuses are seen to consist of tubular structures of simple or arborized patterns having walls, which may be thin and glistening or white and thickened. The sinus tract may arborize and can be tortuous, and the lumen is filled with debris. The preauricular sinuses are often full of keratin and are surrounded by dense connective tissue.
Microscopically, the duct of the sinus is lined with stratified squamous epithelium and contains many cysts along its tract. The connective tissue surrounding the duct may contain hair follicles; sebaceous and sweat glands; and inflammatory tissue, such as lymphocytes, plasma cells, and polymorphonuclear leukocytes.
In one large study, 52% of patients had inflammation of their sinuses, 34% had their sinus abscesses drained, and 18% of sinuses were infected. Infectious agents identified included Staphylococcus epidermidis (31%), Staphylococcus aureus (31%), Streptococcus viridans (15%), Peptococcus species (15%), and Proteus species (8%). Once a patient acquires infection of the sinus, he or she must receive systemic antibiotics. If an abscess is present, it must be incised and drained, and the exudate should be sent for Gram staining and culturing to ensure proper antibiotic coverage.
Once infection occurs, the likelihood of recurrent acute exacerbations is high, and the sinus tract should be surgically removed. Surgery should take place once the infection has been treated with antibiotics and the inflammation has had time to subside. Controversy regarding indications for surgery exists. Some believe that the sinus tract should be surgically extirpated in patients who are asymptomatic because the onset of symptoms and subsequent infection cause scarring, which may lead to incomplete removal of the sinus tract and postoperative recurrences. The recurrence rate after surgery is 13-42% in smaller studies and 21% in one large study.
Most postoperative recurrences occur because of incomplete removal of the sinus tract. One way to prevent incomplete removal is to properly delineate the tract during surgery. Some surgeons cannulate the orifice and inject methylene blue dye into the tract 3 days prior to surgery under sterile conditions. The opening is then closed with a purse-string suture. This technique distends the tract and its extensions by its own secretion stained with methylene blue.
During surgery, some surgeons use either a probe or an injection of methylene blue dye for cannulation of the orifice. The most successful method is to use both modalities to delineate the entire tract.
Other surgical techniques have been studied. The standard technique for extirpation of the sinus tract involves an incision around the sinus and subsequent dissection of the tract to the cyst near the helix. A supposedly more successful technique is the supra-auricular approach, which unlike the former technique, does not allow for difficulties in properly identifying the entire tract. The supra-auricular approach extends the incision postauricularly. Once the temporalis fascia is identified, dissection of the tract begins. A portion of the auricular cartilage, which is attached to the tract, is also removed, decreasing the incidence of recurrence to 5%. Leopardi et al report that they prefer the supra-auricular approach for the surgical treatment of recurring preauricular sinus.
Tan et al reported the most current data in 2005, which suggested that the definitive surgical intervention that promises the best outcome is wide local excision of the sinus, not simple sinectomy. To minimize the risk of recurrence, Tan et al suggest using magnification and intraoperatively opening the sinus and then following from the inside of the sinus to the outside branching tracts of the sinus.
Similarly, Chang and Wu stated in 2005 that the use of an operating microscope can enhance the effectiveness of surgery to remove remnants and help prevent recurrence of a preauricular cyst.
Baatenburg de Jong reports on an "inside-out" technique, which was deemed superior to the classic repair technique, with fewer recurrences, in a small, single-institution study.
Yeo et al found that in a case series of 191 patients with preauricular sinuses (206 surgeries), the recurrence rate following surgery was 4.9%, with surgery under local anesthesia being a risk factor for recurrence (P = .009). Additionally, the cases that involved local infiltrative anesthesia had an increased rate of recurrence compared with surgery performed with the patient under general anesthesia (odds ratio, 6.875).
In a 2007 study from a referral center in Malaya, Tang et al reviewed cases of 71 patients with 73 preauricular sinuses. They found an overall recurrence rate of 14.1% and that 16% of sinuses required drainage of an abscess prior to definitive surgery. Additionally, preauricular sinuses with a previous history of infection or those actively infected during the definitive surgery seemed to be associated with a higher tendency for recurrence. Surgical demonstration of the sinus tract by probing with lacrimal probes or sinus probes, followed by injection of methylene blue, reduces the recurrence rate. Some have advocated a minimal supra-auricular approach without a surgical drain for removal of preauricular sinuses.
Dickson et al found that methylene blue was a safe and useful means of demarcation of preauricular sinuses and branchial sinuses and fistulae in a series of 20 children with preauricular sinuses and 11 with branchial sinuses and fistulae, allowing for smaller incisions and minimal dissections.
In 2010, Bajwa and Kumar reported on radiofrequency thermal ablation versus cold steel” excision for supra-auricular excision of preauricular sinuses. They concluded that radiofrequency-assisted local wide excision appeared to be superior to cold steel excision because the former offered better perioperative visualization, with minimal bleeding and easier dissection. Additionally, they reported that radiofrequency thermal ablation was associated with a lower recurrence rate.
In a 2009 study of the histologic relationship of preauricular sinuses to auricular cartilage, Dunham et al found that sinocartilaginous distances may suggest it can be challenging to dissect most sinus tracts from the cartilage. Thus, the routine removal of a minimal portion of auricular cartilage in combination with the sinus tract can provide a more thorough excision and may stop recurrence.
Consult plastic surgeons or otolaryngologists for surgical treatment.
If the preauricular sinus recurs, it should be fully removed.
If a preauricular sinus is repeatedly infected and the patient does not want surgery, its contents can be cultured and proper antibiotics to cover the pathogens can be given.
Usually, no medications must be given, but if infection occurs, antibiotics can be given. The contents of the sinus should be cultured before antibiotics are prescribed.
If the preauricular sinus becomes repeatedly infected, it can be surgically removed.
Patients may develop infection of the tract with abscess formation. Coatesworth et al described successful management of preauricular sinus abscess that allows drainage of pus with minimal or no disturbance of the sinus.
Infections and ulcerations may occur at a site distant from the opening.
Postoperative recurrence is a complication of preauricular sinus tract extirpation. Several factors contribute to recurrence after surgery, as follows:
Most recurrences occur during the early postoperative period, within 1 month of the procedure. Recurrences should be suspected when discharge from the sinus tract opening persists. The overall incidence of recurrence varies among different studies and ranges from 5-42%.
Winkler et al noted a scalp arteriovenous malformation spontaneously hemorrhaging into a preauricular sinus; it was successfully treated with intravascular embolization and surgical ligation.
Preauricular sinuses generally have a good prognosis.