Definition

An abscess is a painful collection of pus generally caused by a bacterial infection. A preauricular abscess forms in the forepart of the earlobe and is a complication of a congenital abnormality in the outer ear called a preauricular sinus. The preauricular sinus is a hole forming in the earlobe's forepart.

Congenital abnormalities of the external ear occur in approximately 1 in 12,500 births. At least 1-2% of the world's population has preauricular sinuses, making it one of the most common congenital ear disorders. The prevalence varies across countries: 0.1-0.9% in the United States, 0.9% in England, 1.6-2.5% in Taiwan, 4-6% in Asia, and 4-10% in Africa. Despite being common, this condition often goes undiagnosed as it usually does not cause symptoms, and those with symptoms rarely seek medical help due to the mildness of the symptoms.

Causes

The earlobe forms in the sixth week of pregnancy. Genetic factors can cause imperfect development of the outer ear, resulting in a hole or pit forming in the forepart of the earlobe, known as a preauricular sinus. Usually, the preauricular sinus does not cause any symptoms unless it becomes infected.

Preauricular sinuses are lined with epithelial cells that can form cysts. These cysts are susceptible to infection, leading to the formation of a preauricular abscess. Infections are typically caused by bacteria such as Staphylococcus aureus, Streptococcus, Proteus, and Peptococcus species. Bacterial infection leads to irritation, fluid formation, swelling, and pain in the preauricular pit, eventually causing a blockage that results in pus accumulation and abscess formation.

The hearing apparatus and its nerves develop simultaneously with the outer ear during fetal development, so outer ear disorders can be accompanied by inner ear disorders such as deafness.

Risk Factor

• Family history of preauricular sinus
• Skull and facial deformities. Examples of these include branchiootorenal syndrome, Beckwith-Wiedemann syndrome, mandibulofacial dysostosis, oculoauriculovertebral dysplasia, and other chromosomal abnormalities.
• Use of propylthiouracil (PTU) during pregnancy. This hyperthyroidism medication is linked to congenital abnormalities, including urinary system abnormalities (kidney cysts, enlarged kidneys).
• There is no significant difference in the case frequency of preauricular sinus between men and women, but women are more susceptible to preauricular abscesses. This susceptibility is associated with the use of makeup and cosmetics, which can increase the risks of infections.

Symptoms

Common symptoms of a preauricular abscess include:

• Swelling in the forepart of the ear
• Recurrent ear pain
• Recurrent discharge from the forepart of the ear
• Itchy ears
• Redness of the ears
• Headache
• Fever

Once infected, the preauricular sinus is more susceptible to frequent recurrent infections. This is due to residual bacteria in the pit, added to the pit's existence, which increases the risks of further infections. Abscesses often occur in the right ear, likely because the world population is predominantly right-handed.

Diagnosis

A preauricular abscess can usually be diagnosed based on visible symptoms and signs. Laboratory tests, including bacterial culture and antibacterial sensitivity testing, can be performed, especially in recurrent cases. Diagnostic radiology examinations are not routinely required but may be necessary if a sinus or abscess forms in an atypical location or if another abnormality is suspected. Since preauricular sinuses can be accompanied by other congenital abnormalities such as hearing loss or kidney problems. Because of that, individuals with abscesses or preauricular sinuses should be examined for other congenital abnormalities.

Preauricular abscesses can often be misdiagnosed as acne, hair follicle infections, other infections such as tuberculosis, and other congenital conditions like dermoid cysts or sebaceous cysts.

Management

Preauricular sinuses usually do not cause symptoms and do not require therapy. However, a small percentage of cases will experience recurrent infections with inflammation, causing cysts, abscesses, and fluid discharge from the sinus openings.

Medications alone do not eliminate the bacteria in the preauricular sinus. Surgical removal of the abscess and preauricular sinus is the most effective way to eliminate residual bacteria and prevent recurrence and complications.

Treatment usually involves a 10-14 day course of oral antibiotics. The chosen antibiotics regimen usually targets Staphylococcus aureus effectively, such as a combination of amoxicillin and clavulanic acid. Subsequently, pus in the abscess is aspirated using a needle, if possible, to reduce pain and discomfort. If the aspiration procedure is insufficient, an incision-drainage procedure is performed to allow pus to drain out.

Once the infection is controlled, the preauricular sinus is surgically removed, especially in cases of recurrent or persistent infection. Individuals with suppressed immune systems or severe illness may require intravenous antibiotics followed by surgical drainage.

Therapy for preauricular abscesses remains controversial and can vary depending on the healthcare facilities. Some facilities may avoid procedures like incision and drainage for cosmetic reasons, while others may adhere to these procedures for their effectiveness in clearing infections.

Complications

If left untreated, the infection can spread to nearby structures such as the earlobe, ear canal, and temporomandibular joint (TMJ). Abscesses can also cause excessive scarring or keloids, which can be cosmetically unappealing.

Infected preauricular sinuses can lead to chronic or long-term abscesses. This occurs when the abscess wall is damaged, allowing pus or fluid to leak out and infect surrounding tissues.

Even with careful surgical removal, recurrence can occur due to residual cyst wall or abscess material left in the surgical site. The recurrence rate is estimated to be between 0-42%.

Prevention

While the formation of preauricular sinuses cannot be prevented due to their congenital nature, the development of preauricular abscesses can be minimized by maintaining good hygiene. Some studies suggest that prophylactic removal of asymptomatic preauricular sinuses can be performed to avoid future infections and abscesses. This surgical procedure should be conducted by an experienced otolaryngologist and neck surgeon, typically under general anesthesia.

When to see a doctor?

If you have a preauricular sinus that does not cause any symptoms, you generally do not need treatment and should simply monitor for any changes. If you notice signs of infection such as redness, swelling, pain, or fluid discharge from the preauricular sinus, you should promptly consult a doctor. An infected preauricular sinus, particularly one that has formed an abscess, requires appropriate treatment to avoid complications.