What can cause unilateral earlobe swelling and erythema with no signs of infection, a normal external ear canal, and a normal tympanic membrane (TM) in a patient with a history of autoimmune disorders, such as Sjögren's syndrome or type 1 diabetes?

Unilateral Earlobe Swelling and Erythema: Differential Diagnosis

The most likely causes of isolated unilateral earlobe swelling and erythema with a normal ear canal and tympanic membrane are contact dermatitis (from jewelry, cosmetics, or hearing aids), localized cellulitis of the earlobe, or—given the patient's autoimmune history—cutaneous manifestations of Sjögren's syndrome such as annular erythema. 1, 2

Primary Diagnostic Considerations

Contact Dermatitis (Most Common)

• Nickel allergy from pierced earrings affects approximately 10% of women and is a leading cause of earlobe dermatitis 1
• Hearing aid materials (silicone, methyl-methacrylate), earplugs, cosmetics, or hair products can trigger allergic or irritant contact dermatitis 1
• The presentation typically includes erythema, swelling, and pruritus localized to the area of contact 1
• Immediately discontinue any potential sensitizing agents including jewelry, hearing aids, or topical products applied to the ear 1

Localized Cellulitis of the Earlobe

• Bacterial infection of the earlobe soft tissue, distinct from otitis externa, can occur following trauma (including ear piercing) or insect bites 3
• The earlobe itself becomes swollen, erythematous, and tender, but the external auditory canal remains normal 3
• This represents extension of infection to periauricular tissues rather than ear canal involvement 4

Autoimmune-Related Cutaneous Manifestations

Given the patient's history of Sjögren's syndrome:

• Annular erythema associated with Sjögren's syndrome (AESS) can present as erythematous lesions on the ears and face, with 75% of cases positive for both anti-SSA and anti-SSB antibodies 2
• Sjögren's syndrome causes cutaneous manifestations in nearly half of patients, including dry skin, purpura, and urticaria-like lesions 5
• AESS responds to low-dose oral prednisolone (approximately 10 mg daily), which has a more rapid clinical effect than topical steroids 2
• Cutaneous vasculitis associated with Sjögren's can present as palpable or nonpalpable purpura, though this typically involves multiple sites 5

Critical Differentiation from Otitis Externa

This presentation is NOT otitis externa because:

• Otitis externa involves inflammation of the external auditory canal with ear canal edema, erythema, and debris—all absent in this case 6
• The hallmark sign of otitis externa is tenderness with manipulation of the tragus or pinna, which would be present if the ear canal were involved 7, 6
• The normal ear canal and tympanic membrane exclude acute otitis externa and acute otitis media 7, 6

Diagnostic Approach

History to Obtain

• Recent jewelry changes, new earrings, or prolonged wearing of nickel-containing jewelry 1
• Use of hearing aids, earplugs, or new cosmetic/hair products 1
• Recent trauma to the earlobe, including ear piercing 3
• Systemic symptoms suggesting autoimmune flare (dry eyes, dry mouth worsening, joint pain, fatigue) 5, 2
• Presence of similar lesions elsewhere on the body 5, 2

Physical Examination Findings to Document

• Precise location and extent of erythema and swelling (earlobe only vs. periauricular extension) 4
• Presence or absence of tragal tenderness (should be absent if ear canal uninvolved) 7, 6
• Skin texture changes, scaling, or vesiculation suggesting dermatitis 1
• Annular or polycyclic configuration suggesting AESS 2
• Signs of systemic vasculitis (purpura elsewhere) 5

Management Algorithm

For Suspected Contact Dermatitis

• Remove all potential allergens immediately (jewelry, hearing aids, topical products) 1
• Apply hydrocortisone 1% otic solution or ointment to the affected earlobe twice daily for 7-10 days, extending to 14 days if symptoms persist 1
• Never use neomycin-containing products, as they cause contact sensitivity in 13-30% of patients with chronic external otitis 4, 1
• Avoid water exposure and irritants during active treatment 1

For Suspected Cellulitis

• If periauricular extension is present (swelling beyond the earlobe), systemic antibiotics covering Staphylococcus aureus are required 4
• Oral antibiotics such as cephalexin or dicloxacillin for 7-10 days are appropriate first-line choices 3
• Reassess within 48-72 hours to ensure improvement 4

For Suspected Autoimmune Etiology (Sjögren's-Related)

• If annular erythema pattern is present with known Sjögren's syndrome, consider low-dose oral prednisolone (approximately 10 mg daily) 2
• Check anti-SSA and anti-SSB antibodies if not previously documented 2
• Evaluate for systemic manifestations requiring higher steroid doses 2
• Consider rheumatology consultation for management of underlying autoimmune disease 5, 2

Common Pitfalls to Avoid

• Do not prescribe topical antibiotics for isolated earlobe dermatitis without clear signs of bacterial superinfection 1
• Avoid neomycin-containing combination products entirely due to high sensitization risk 4, 1
• Do not assume otitis externa when the ear canal examination is normal 6
• Do not overlook systemic autoimmune manifestations that may require escalation of therapy 5, 2
• Failing to remove the offending allergen will result in treatment failure regardless of topical therapy 1

When to Reassess or Escalate

• Reassess within 48-72 hours if no improvement with initial management 4, 1
• Consider biopsy if lesions persist beyond 2 weeks despite appropriate treatment or if vasculitis is suspected 5, 2
• Escalate to rheumatology if systemic autoimmune flare is suspected 5, 2
• Consider dermatology referral for patch testing if contact dermatitis is refractory or recurrent 1