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Abscess of preauricular sinus — Clinical Guidelines

Overview

Preauricular sinus (PAS) is a congenital malformation characterized by an abnormal opening or pit located near the external ear, typically at the anterior margin of the ascending limb of the helix. It is relatively common, with an incidence ranging from 0.1% to 0.9% in European and American populations 1 7. While often asymptomatic, PAS poses a significant clinical challenge due to its high risk of infection, abscess formation, and recurrence following surgical intervention. Proper management is crucial to prevent complications and ensure optimal outcomes, making accurate diagnosis and effective treatment essential in day-to-day practice 1 4.

Pathophysiology

The exact etiology of preauricular sinuses remains unclear, but they are generally considered to arise from aberrant embryological development during the sixth to eighth weeks of gestation, specifically involving the first and second pharyngeal arches 7. These developmental anomalies result in persistent tracts connecting the skin surface to underlying structures, often including cartilage or fibrous tissue. The presence of these tracts predisposes individuals to recurrent infections and abscess formation due to the accumulation of debris and bacteria within the sinus tract 1 12. Chronic inflammation and repeated episodes of infection can further complicate the healing process, contributing to higher recurrence rates following standard surgical techniques 10.

Epidemiology

Preauricular sinuses exhibit a relatively consistent incidence across different populations, with estimates ranging from 0.1% to 0.9% 1 7. They are slightly more common on the right side and can occur bilaterally in about 25-50% of cases, which may suggest a genetic component given the increased likelihood of inheritance in bilateral presentations 9. Age distribution shows that these anomalies are typically identified early in life, often during infancy or early childhood, though they can remain asymptomatic until later stages 6. Geographic variations are minimal, with similar prevalence noted across Europe and the United States, though specific regional studies might reveal slight differences 1 7.

Clinical Presentation

Preauricular sinuses are often asymptomatic and discovered incidentally during routine physical examinations or when complications arise. Typical presentations include small pits or depressions near the ear, usually measuring a few millimeters in diameter 7. However, atypical presentations can occur, such as postauricular cysts mimicking other conditions like sebaceous cysts or furuncles 8. Red-flag features include recurrent purulent discharge, abscess formation, and signs of systemic infection like fever and malaise 12. These complications necessitate prompt medical attention to prevent further morbidity 4.

Diagnosis

The diagnosis of preauricular sinuses primarily relies on clinical examination, often supplemented by imaging when complications or atypical presentations are suspected. Specific criteria for diagnosis include:

Clinical Examination: Identification of a pit or opening near the anterior margin of the ascending helix of the ear 7.

Imaging: In cases of complex or atypical presentations, ultrasound or CT scans can help delineate the extent of the sinus tract and associated structures 8.

Histopathology: Rarely needed but can confirm the presence of sinus tracts and associated inflammatory changes if surgical exploration is performed 11.

Differential Diagnosis:

Sebaceous Cysts: Typically unilocular and filled with keratin, lacking the tract connection seen in PAS 12.

Furuncles: Localized, painful, and often fluctuant lesions without the persistent tract characteristic of PAS 12.

Branchial Cleft Fistulae: Usually located more inferiorly along the neck and associated with a different embryological origin 7.

Management

Initial Management

Medical Therapy: For uncomplicated cases, initial management may involve cleaning the sinus tract and topical or systemic antibiotics to treat infections 12.

- Topical Antibiotics: Apply as needed for superficial infections. - Systemic Antibiotics: Consider for moderate to severe infections (e.g., amoxicillin-clavulanate 875 mg/125 mg twice daily for 7-10 days) 12.

Surgical Management

Primary Surgical Excision: Recommended for definitive treatment to prevent recurrence.

- Supra-auricular Approach: Preferred due to lower recurrence rates compared to simple sinectomy 1. - Technique: Dissection along the supra-auricular region to ensure complete tract removal. - Contraindications: Active severe infection requiring initial medical stabilization 4. - Figure 8 Incision with Extended Fistulectomy: An advanced technique for complex cases to ensure complete excision 5. - Technique: Dual incisions around the sinus tract to enhance exposure and removal. - Post-operative Care: Close monitoring for signs of infection and meticulous wound care 5.

Refractory Cases

Recurrent Infections or Recurrence: Consider referral to a specialist (otolaryngologist) for advanced surgical techniques or further evaluation.

- Methylene Blue Injection: Prior to surgery to delineate the tract, followed by purse-string closure and posterior drainage 11. - Procedure: Inject methylene blue into the tract, close the orifice, and drain the area post-operatively. - Monitoring: Regular follow-up to assess healing and recurrence 11.

Complications

Recurrent Infections: Common, especially in inadequately treated or recurrent cases.

- Management: Prompt antibiotic therapy and surgical reevaluation if necessary 10.

Abscess Formation: Can occur secondary to chronic infection, requiring drainage and appropriate antibiotic coverage 12.

Surgical Complications: Wound infections, scarring, and incomplete excision leading to recurrence 10.

- Preventive Measures: Meticulous surgical technique, appropriate post-operative care, and early intervention for signs of infection 10.

Prognosis & Follow-up

The prognosis for preauricular sinus management is generally good with appropriate surgical intervention, though recurrence rates remain a concern, particularly with less meticulous techniques. Key prognostic indicators include:

Surgical Technique: Supra-auricular approach and complete tract excision significantly reduce recurrence 1.

Post-operative Care: Adequate wound care and monitoring for signs of infection are crucial 10.

Follow-up Intervals:

Initial: Within 1 week post-surgery for wound inspection.

Subsequent: Every 3-6 months for the first year to monitor for recurrence or complications 5.

Special Populations

Pediatric Patients: Early surgical intervention is often necessary due to higher infection risks in younger children 4.

- Considerations: Anesthesia risks, psychological impact, and parental counseling 4.

Comorbidities: Patients with chronic conditions like renal abnormalities should undergo thorough evaluation for associated anomalies 6.

- Screening: Renal ultrasound may be warranted in cases with complex or bilateral sinuses 7.

Key Recommendations

Primary Surgical Excision: Use the supra-auricular approach to minimize recurrence rates (Evidence: Strong 1).

Early Intervention for Infections: Initiate prompt antibiotic therapy for infected sinuses and consider early surgical intervention if necessary (Evidence: Moderate 12).

Comprehensive Surgical Technique: Ensure meticulous dissection and complete tract removal to prevent recurrence (Evidence: Strong 10).

Post-operative Monitoring: Regular follow-up visits are essential, especially within the first year post-surgery, to detect and manage complications early (Evidence: Moderate 5).

Consideration of Complex Cases: Refer to otolaryngology for advanced techniques in recurrent or complex cases (Evidence: Expert opinion 5).

Screening for Associated Anomalies: Evaluate for congenital ear and renal abnormalities, particularly in bilateral cases (Evidence: Moderate 6).

Use of Methylene Blue: For complex cases, consider methylene blue injection to delineate the tract prior to surgery (Evidence: Weak 11).

Avoid Local Anesthesia in Recurrent Cases: Local anesthesia may increase recurrence risk; consider general anesthesia for repeat surgeries (Evidence: Moderate 10).

Preventative Measures Against Infection: Implement rigorous post-operative wound care and monitor for signs of infection (Evidence: Strong 10).

Parental Counseling: Provide comprehensive counseling for pediatric patients regarding the surgical process and expected outcomes (Evidence: Expert opinion 4).

References

1 Leopardi G, Chiarella G, Conti S, Cassandro E. Surgical treatment of recurring preauricular sinus: supra-auricular approach. Acta otorhinolaryngologica Italica : organo ufficiale della Societa italiana di otorinolaringologia e chirurgia cervico-facciale 2008. link 2 Chen J, Zhou P, Zuo J, Ming W, Huang T, Tao Z. Variant Types of Preauricular Sinuses: Classifications, Clinical Presentation and Management. The Laryngoscope 2024. link 3 Bruijnzeel H, van den Aardweg MT, Grolman W, Stegeman I, van der Veen EL. A systematic review on the surgical outcome of preauricular sinus excision techniques. The Laryngoscope 2016. link 4 Shim HS, Kim DJ, Kim MC, Lim JS, Han KT. Early one-stage surgical treatment of infected preauricular sinus. European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery 2013. link 5 Huang WJ, Chu CH, Wang MC, Kuo CL, Shiao AS. Decision making in the choice of surgical management for preauricular sinuses with different severities. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery 2013. link 6 Huang XY, Tay GS, Wansaicheong GK, Low WK. Preauricular sinus: clinical course and associations. Archives of otolaryngology--head & neck surgery 2007. link 7 Tan T, Constantinides H, Mitchell TE. The preauricular sinus: A review of its aetiology, clinical presentation and management. International journal of pediatric otorhinolaryngology 2005. link 8 Chang PH, Wu CM. An insidious preauricular sinus presenting as an infected postauricular cyst. International journal of clinical practice 2005. link 9 Scheinfeld NS, Silverberg NB, Weinberg JM, Nozad V. The preauricular sinus: a review of its clinical presentation, treatment, and associations. Pediatric dermatology 2004. link 10 Currie AR, King WW, Vlantis AC, Li AK. Pitfalls in the management of preauricular sinuses. The British journal of surgery 1996. link 11 Lau JT. Towards better delineation and complete excision of preauricular sinus. The Australian and New Zealand journal of surgery 1983. link 12 Baarsma EA. Surgical treatment of the infected preauricular sinus. Archives of oto-rhino-laryngology 1979. link

Abscess of preauricular sinus