Harvey's Garden

Collection of dermatological disorders

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aliases

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Dyshidrotic eczema

  • Etiology & Risk Factors
    • Young adults (<40 yo) with atopic diathesis (atopic dermatitis, asthma, allergic rhinitis).
    • Triggers: Hyperhidrosis, frequent wet work/handwashing, nickel/contact allergens, emotional stress.
  • Clinical Presentation
    • Intense pruritus or burning preceding lesions.
    • “Tapioca pudding” vesicles: Deep-seated, tense, clear vesicular clusters.
    • Distribution: Lateral fingers/toes, palms, and soles (classically symmetric).
    • Late stage: Scaling, desquamation, lichenification, and painful fissures.
  • Diagnosis
    • Clinical diagnosis based on history and characteristic lesions.
    • KOH prep: Essential initial step to rule out dermatophyte infection (Tinea).
    • Patch testing: Indicated for recurrent/chronic cases to identify contact allergens.
  • High-Yield Differentials
    • Tinea manuum/pedis: (+) KOH (branching hyphae), asymmetric (“two feet, one hand”).
    • Scabies: Nocturnal pruritus, burrows in web spaces, (+) mineral oil scraping for mites/eggs.
    • Herpetic whitlow: Severe localized pain (not itch), single digit, (+) HSV PCR.
    • Palmoplantar pustulosis: Primary sterile yellow pustules, not clear vesicles.
  • Management
    • General: Emollients (petrolatum), avoid harsh soaps/wet work, wear cotton gloves.
    • 1st-line: Super-high-potency topical corticosteroids (e.g., Clobetasol 0.05% ointment).
    • Severe/Disabling: Short taper of oral corticosteroids (e.g., Prednisone).
    • Refractory/Maintenance: Topical calcineurin inhibitors (Tacrolimus), phototherapy (PUVA/narrowband UV-B), or Dupilumab.
  • Complications
    • Secondary bacterial superinfection (most commonly Staphylococcus aureus impetiginization/cellulitis).

Miliaria

  • Pathophysiology: Occlusion of eccrine sweat ducts causing sweat extravasation into skin layers.
  • Risk Factors: Neonates (immature sweat glands), hot/humid environments, febrile illness, over-bundling, and occlusive dressings/ointments.
  • Clinical Variants:
    • Miliaria crystallina (stratum corneum): Asymptomatic, fragile 1–2 mm clear superficial vesicles without erythema (“dewdrops”); easily ruptured by light friction.
    • Miliaria rubra (“prickly heat”; intraepidermal): Intensely pruritic/burning, erythematous non-follicular papules and microvesicles in flexural areas and trunk.
    • Miliaria profunda (dermal): Firm, flesh-colored, asymptomatic papules/nodules; typically follows recurrent episodes of rubra.
  • Key Differentials:
    • Erythema toxicum neonatorum: Spares palms/soles; pustules show eosinophils on Wright stain (miliaria does not).
    • Neonatal cephalic pustulosis (neonatal acne): Confined to face/cheeks; non-pruritic; lacks comedones.
    • Folliculitis: Centered strictly on hair follicles (miliaria is non-follicular/eccrine).
  • Diagnosis: Clinical; no laboratory workup or biopsy indicated.
  • Management:
    • First-line: Cooling and air exposure (AC, remove excessive/tight clothing, cool baths, avoid occlusive petroleum-based ointments).
    • Symptomatic relief (rubra): Low-potency topical corticosteroids (e.g., hydrocortisone 1%) or calamine lotion.
    • Secondary superinfection: Topical mupirocin or oral anti-staphylococcal Abx (e.g., cephalexin) if secondary S. aureus impetigo develops.
  • Complications: Secondary bacterial infection, localized anhidrosis, and impaired thermoregulation leading to heat exhaustion/heat stroke.

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