What are the main etiological entities of preauricular collections?

Main Etiological Entities of Preauricular Collections

Preauricular collections are most commonly caused by infections of congenital preauricular sinuses, but can also result from various viral, bacterial, mycobacterial, and neoplastic processes that affect the preauricular region.

Congenital Causes

• Preauricular sinuses (ear pits) are common congenital abnormalities that appear as small dells adjacent to the external ear near the anterior margin of the ascending limb of the helix, most frequently on the right side 1
• These sinuses can be either inherited (showing an incomplete autosomal dominant pattern with reduced penetrance and variable expression) or sporadic 1
• Bilateral preauricular sinuses occur in 25-50% of cases, increasing the likelihood of being inherited 1
• Preauricular sinuses are features of other conditions or syndromes in 3-10% of cases, primarily in association with deafness and branchio-oto-renal (BOR) syndrome 1

Infectious Causes

Bacterial Infections

• Gram-positive bacteria are the most common infectious agents in preauricular sinuses/cysts 1
• Infected preauricular sinuses can present as abscesses requiring antibiotic treatment, needle aspiration, or incision and drainage 2
• Chronic preauricular abscesses can develop and may require surgical management 2
• Gonococcal infections can present with preauricular lymphadenopathy and may lead to severe purulent conjunctivitis 3

Mycobacterial Infections

• Tuberculosis can manifest as preauricular sinus abscesses, especially in endemic regions 4
• Mycobacterial infections typically cause chronic, recurrent disease with poor wound healing 4
• Testing for acid-fast bacilli is recommended in recurrent cases and extensive infections despite the absence of systemic or pulmonary symptoms 4

Viral Infections

• Viral conjunctivitis often presents with preauricular lymphadenopathy, particularly in adenoviral infections 3
• Herpes simplex virus (HSV) can cause unilateral conjunctivitis with palpable preauricular nodes 3
• Varicella (herpes) zoster can present with preauricular lymphadenopathy along with vesicular dermatomal rash 3
• Epstein-Barr virus can cause follicular conjunctivitis with preauricular lymphadenopathy 3

Inflammatory/Immunological Causes

• Parinaud oculoglandular syndrome presents with unilateral granulomatous follicular conjunctivitis and ipsilateral regional preauricular and submandibular lymphadenopathy 3
• Most commonly associated with cat scratch disease (Bartonella henselae), tularemia (Francisella tularensis), and sporotrichosis 3
• Also reported with various bacterial, fungal, mycobacterial, and viral infections 3

Neoplastic Causes

• Ocular surface squamous neoplasia can present with conjunctival hyperemia and may be mistaken for chronic inflammation 3
• Melanoma can appear as a painless, flat or nodular lesion that may involve the preauricular region 3

Management Considerations

• For infected preauricular sinuses/cysts, control of infection prior to definitive surgery is desirable but not mandatory 2
• Treatment options include oral antibiotics, needle aspiration, and/or incision and drainage 2, 5
• Evidence suggests that incision and drainage of infected preauricular cysts may be associated with higher recurrence rates (18.5%) compared to antibiotic therapy or fine-needle aspiration (3.3%) 5
• Definitive treatment for symptomatic or recurrently infected preauricular sinuses is complete surgical excision 1
• Recurrence rates after surgery range from 9% to 42%, with meticulous excision by an experienced surgeon minimizing this risk 1

Clinical Pearls

• When preauricular collections are associated with other congenital anomalies, auditory testing and renal ultrasound should be considered 1
• For mycobacterial infections, treatment with anti-tuberculous drugs should be commenced before elective sinus excision 4
• In cases of recurrent or persistent infection, wide local excision of the sinus offers more favorable outcomes compared to simple sinectomy 6