Preauricular Sinus

A preauricular sinus is a congenital blind ending epithelial lined tract that opens near the anterior margin of the ascending helix of the ear. It is a harmless variant until it becomes infected.

It is found in 0.1% to 0.9% of people in Europe and the United States, 4% to 10% in parts of Africa and Asia. It is usually unilateral (about 75%), more often on the right, and is inherited as an autosomal dominant trait with variable penetrance. It is sometimes associated with hearing loss, branchio-oto-renal syndrome and renal anomalies.

Pathophysiology.

It results from incomplete fusion of the auricular hillocks of the first and second branchial arches. The tract is lined by squamous epithelium with sebaceous glands, and obstruction leads to retained debris, abscess formation and recurrent infection.

A small pit in front of the helix, sometimes with intermittent white discharge. Infection causes pain, redness, swelling, abscess and pus discharge. Recurrences are common, and scarring develops.

Red flags.

• Fever with spreading cellulitis.
• Recurrent abscess with a facial nerve palsy.
• Hearing loss or other anomalies (branchio-oto-renal syndrome).

Diagnosis is clinical. A swab of pus is sent for culture in abscess. In bilateral sinuses, a family history of deafness, neck pits or renal disease, audiometry and renal ultrasound are done. Ultrasound or MRI defines deep extension in recurrent disease.

Differential diagnosis.

• First branchial cleft anomaly.
• Sebaceous cyst.
• Infected hair follicle.
• Ear canal infection.
• Perichondritis.

Asymptomatic sinuses need no treatment. Treat infection with antibiotics and drain a fluctuant abscess by incision, then excise the sinus completely (including the tract and surrounding cartilage) once inflammation has settled, to prevent recurrence.

• Flucloxacillin: 500 mg orally four times daily for 7 days (1 g four times daily for severe infection); maximum 4 g daily; monitor liver tests with courses over 14 days and for rash; reduce frequency in severe renal impairment; children 12.5 to 25 mg/kg four times daily.
• Clindamycin (penicillin allergy): 300 to 450 mg orally four times daily for 7 days; maximum 1.8 g daily; monitor for diarrhoea and Clostridioides difficile infection; no renal adjustment; children 3 to 6 mg/kg four times daily.

Monitoring. Review after 48 hours of antibiotic treatment and after drainage; check wound healing after excision.

Referral and escalation. ENT or paediatric surgery for recurrent infection and elective excision.

Special groups. Children need weight based dosing and surgery after at least 4 to 6 weeks without infection.