What is the diagnosis and treatment for a patient presenting with itching on the chest and axillary area, accompanied by multiple small pustular vesicles?

Diagnosis: Miliaria Rubra (Prickly Heat) or Folliculitis

The clinical presentation of itching with multiple small pustular vesicles (~1mm) on the chest and axillary areas most likely represents either miliaria rubra (prickly heat) or bacterial folliculitis, both of which require different treatment approaches based on the predominant lesion type.

Clinical Assessment

The key diagnostic features to differentiate these conditions include:

• Lesion characteristics: True 1mm pustules suggest bacterial folliculitis (typically Staphylococcus aureus), while tiny vesicles on an erythematous base with intense pruritus favor miliaria rubra 1
• Distribution pattern: Both conditions commonly affect intertriginous areas (axillae) and the chest where occlusion and sweating occur 2
• Associated symptoms: Burning/stinging sensation with sudden onset suggests irritant contact dermatitis or miliaria, while gradual onset with follicular-centered lesions indicates folliculitis 3

Critical differential diagnoses to exclude:

• Scabies (look for burrows, inguinal/genital involvement, palmoplantar vesicles in infants) 2
• Contact dermatitis (should have visible borders and history of exposure) 1
• Eczematous dermatitis (typically has oozing, crusting, and less discrete pustules) 2

Treatment Approach

For Bacterial Folliculitis (if pustules predominate):

Primary treatment consists of topical antibiotics and antiseptic measures:

• Topical fusidic acid or mupirocin applied twice daily to affected areas for 7-10 days 4
• If secondary bacterial infection is evident (crusting, weeping), oral antibiotics are indicated: flucloxacillin for Staphylococcus aureus or erythromycin for penicillin allergy 5
• Antiseptic washes (chlorhexidine or benzoyl peroxide) to reduce bacterial colonization 5

For Miliaria Rubra (if vesicles predominate):

Treatment focuses on reducing heat and moisture:

• Cool compresses and keeping the affected areas dry and cool 6
• Avoid occlusive clothing; recommend loose cotton garments 5
• Mild topical corticosteroids (hydrocortisone 1%) for pruritus if needed, applied twice daily for 3-5 days 6, 7
• Oral antihistamines with sedative properties (hydroxyzine, diphenhydramine) for severe pruritus, particularly at night 6, 5

Symptomatic Management (for both conditions):

• Avoid irritants: Stop using soaps and detergents; use dispersible cream as soap substitute 6, 5
• Emollients: Apply non-greasy moisturizers after bathing to maintain skin barrier 6
• Oral antihistamines: Cetirizine, loratadine, or fexofenadina for moderate to severe itching 6

Common Pitfalls to Avoid

• Do not use potent topical corticosteroids in intertriginous areas due to increased absorption and risk of skin atrophy 2, 7
• Avoid greasy products that can inhibit wound exudate absorption and promote superinfection 6
• Do not use alcohol-containing preparations on inflamed skin as they worsen dryness 6
• Avoid overuse of non-sedating antihistamines which have limited value for pruritus in dermatitis 6

When to Escalate Care

If the condition worsens despite treatment or spreads beyond 50% body surface area, consider:

• Systemic bacterial infection requiring hospitalization 2
• Alternative diagnoses such as eczema herpeticum (requires oral acyclovir) 5
• Severe contact dermatitis requiring systemic corticosteroids (prednisone tapered over 2-3 weeks) 1