What is the appropriate workup and treatment for a patient presenting with an axillary rash?

Workup and Management of Axillary Rash

For a patient presenting with an axillary rash, begin with targeted history focusing on medication use (especially deodorants containing zirconium or aluminum), recent systemic symptoms (fever, malaise), and distribution pattern, followed by physical examination to classify the rash morphology (erythematous, vesiculobullous, petechial, or maculopapular) and assess for systemic involvement. 1, 2

Initial Clinical Assessment

Critical History Elements

• Medication and product exposure: Specifically ask about deodorant use, as zirconium-containing products can induce allergic axillary granulomas 3
• Systemic symptoms: Presence of fever dramatically narrows the differential and suggests potentially life-threatening conditions requiring urgent evaluation 4, 1
• Recent travel history: Broadens differential to include resurgent viral diseases like measles 4
• Timeline and progression: Acute onset (<24-48 hours) versus chronic/recurrent pattern 2

Physical Examination Priorities

• Morphologic classification: Categorize as petechial/purpuric, erythematous, maculopapular, or vesiculobullous, as this determines the diagnostic algorithm 1
• Distribution assessment: Note if confined to axillae or part of generalized eruption, and whether neck/head are involved 5, 2
• Mucosal involvement: Check oral mucosa, conjunctivae, and genital areas—presence suggests serious conditions like Stevens-Johnson syndrome 6
• Lymphadenopathy: Palpate axillary nodes; enlarged nodes require ultrasound evaluation to exclude malignancy 7

Diagnostic Algorithm Based on Morphology

For Erythematous/Eczematous Rash (Most Common in Axillae)

• Grade 1 (localized, <10% body surface): Likely contact dermatitis or irritant reaction; no immediate workup needed 5, 8
• Grade 2 (diffuse, 10-50% body surface): Consider dermatology consultation; may represent drug reaction 5
• Grade 3 (>50% body surface) or systemic symptoms: Urgent evaluation for DRESS syndrome or Stevens-Johnson syndrome; requires hospitalization 5

For Vesiculobullous Lesions

• If patient >70 years without atrophic scars or mucosal involvement: Consider bullous pemphigoid; obtain skin biopsy for direct immunofluorescence (DIF) 8
• If targetoid lesions present: Evaluate for erythema multiforme or Stevens-Johnson syndrome; check for recent medication changes 6

For Petechial/Purpuric Rash with Fever

• This is a medical emergency: Immediately evaluate for meningococcemia or other life-threatening infections; obtain blood cultures, CBC, coagulation studies 1

Specific Workup Recommendations

When Dermatology Consultation is Indicated

• Grade 2 or higher eczematous dermatitis (>10% body surface area) 5, 8
• Any vesiculobullous eruption in elderly patients 8
• Presence of targetoid lesions with mucosal involvement 6
• Suspected DRESS or Stevens-Johnson syndrome 5

When Imaging is Required

• Axillary ultrasound: If palpable lymphadenopathy present to exclude malignancy 7
• Diagnostic mammography: If lymph nodes suspicious on ultrasound to evaluate for occult breast cancer 7

Laboratory Testing

• Not routinely needed for localized contact dermatitis or irritant reactions 2
• Obtain if systemic symptoms present: CBC, comprehensive metabolic panel, eosinophil count (for DRESS) 5
• Skin biopsy with DIF: For suspected bullous pemphigoid in patients >70 years 8

Treatment Approach

For Localized Eczematous Dermatitis (<10% BSA)

• First-line: Superpotent topical corticosteroids (triamcinolone acetonide 0.1% cream applied 2-3 times daily) 8, 9
• Escalate to systemic therapy if no improvement within 3-7 days 8
• Avoid occlusive dressings in axillary area due to increased systemic absorption risk 9

For Moderate to Extensive Disease (>10% BSA)

• Systemic corticosteroids: Prednisone 0.5-0.75 mg/kg/day; never exceed 0.75 mg/kg/day in elderly patients due to increased mortality risk 8
• Discontinue all suspected triggering agents (deodorants, new medications) 5, 3

For Suspected DRESS or Stevens-Johnson Syndrome

• Immediately discontinue all potential causative medications 5
• Emergency hospitalization required 5
• Do not use topical corticosteroids alone; systemic therapy needed 5

Critical Pitfalls to Avoid

• Do not dismiss axillary rash as simple contact dermatitis if fever, mucosal involvement, or systemic symptoms present—these indicate potentially life-threatening conditions 5, 1
• Do not delay biopsy of suspicious axillary lymph nodes; early diagnosis of occult malignancy significantly impacts prognosis 7
• Do not use high-dose systemic corticosteroids (>0.75 mg/kg/day) in elderly patients with bullous pemphigoid due to documented increased mortality 8
• Do not apply occlusive dressings to axillary areas when using topical corticosteroids, as this increases systemic absorption and HPA axis suppression risk 9

Follow-Up Strategy

For Localized Disease on Topical Therapy

• Reassess at 3-7 days; if no improvement, escalate to systemic therapy 8
• Monitor for steroid side effects if prolonged use required 8

For Systemic Corticosteroid Therapy

• Initial phase (first 3 months): Follow-up every 2 weeks to assess response and adjust therapy 8
• Maintenance phase: Monthly visits with gradual dose reduction when disease controlled ≥1 month 8