derma and allergy

Dermatology and Allergy in Pediatrics

Overview of Skin Lesions

Understanding skin lesions is vital in pediatric dermatology, particularly knowing the types of primary and secondary skin lesions.

Primary Skin Lesions

  1. Macule:

    • Definition: Flat, non-palpable lesions.

    • Morphology: Circumscribed skin discoloration.

    • Examples: Café au lait spots, vitiligo, freckles, junctional nevi, ink tattoos, tinea versicolor, melasma.

  2. Patch:

    • Definition: Larger macule, typically >1 cm.

    • Examples: Same as macules, plus nevus flammeus.

  3. Papule:

    • Definition: Solid elevation <0.5 cm in diameter.

    • Examples: Acrochordon (skin tag), acne, nevus, melanoma, molluscum contagiosum.

  4. Plaque:

    • Definition: Broad papule or confluence of papules >0.5 cm.

    • Examples: Psoriasis, eczema, tinea corporis, Mycosis fungoides.

  5. Nodule:

    • Definition: Solid elevation >0.5 cm in diameter.

    • Examples: Rheumatoid nodule, xanthoma, larger deeper papules, lipoma, metastatic carcinoma.

  6. Tumor:

    • Definition: Large nodules.

    • Examples: Lipomas, melanoma, tuberculosis (TB).

  7. Wheal:

    • Definition: Evanescent, pruritic and edematous plaques.

    • Examples: Urticaria, urticaria pigmentosum.

  8. Vesicle:

    • Definition: Papule filled with clear fluid (blister).

    • Examples: Herpes simplex, herpes zoster, contact dermatitis, poison ivy dermatitis.

  9. Pustule:

    • Definition: Vesicle or bulla filled with purulent fluid.

    • Examples: Acne, carbuncles.

  10. Cyst:

    • Definition: Encapsulated, fluid-filled mass originating in the subcutaneous tissue or dermis.

    • Examples: Sebaceous cysts, epidermoid cysts.

  11. Bulla:

    • Definition: Large distinct elevation with fluid.

    • Examples: Large friction or burn blisters.

Secondary Skin Lesions

  1. Erosion: Loss of the epidermis that does not extend into the dermis. Example: Ruptured chickenpox vesicle.

  2. Ulcer: Loss of skin through the epidermis, typically leading to scar formation. Example: Stasis ulcer.

  3. Fissure: A split down through all epidermal layers of skin. Example: Athlete's foot.

  4. Atrophy: Thinning of the epidermal surface, causing the skin to appear translucent. Example: Arterial insufficiency.

  5. Excoriation: Loss of outer skin layers due to scratching or rubbing. Example: Scratched insect bite.

  6. Crust: Collection of serous exudate and debris on the skin surface. Example: Impetigo.

  7. Scale: Compact portion of desquamating stratum corneum, varying in size and thickness. Example: Psoriasis scale.

  8. Lichenification: Epidermal thickening with increased visibility of furrows. Example: Chronic atopic dermatitis.

  9. Scar: Fibrous tissue replacement of lost epidermal/dermal tissue. Example: Surgical or acne scars.

  10. Keloid: Hyperplastic scar tissue forming a significant elevation on the skin. Example: Postsurgical scar.

The Allergy Cascade

Understanding Allergy

Allergies can have varying types based on the immunological response.

Allergic Reactions

  • Immediate Reaction: Involves the release of mediators like histamine, leukotrienes, and cytokines. This typically results in rapid symptoms following allergen exposure.

  • Late Phase Reaction: Occurs hours after the immediate reaction, characterized by inflammation.

Anaphylaxis

  • Definition: A potentially fatal, multi-organ reaction triggered by allergen exposure. Can be IgE dependent or non-IgE dependent. Acute symptoms can occur alongside respiratory distress or organ dysfunction.

  • Management:

    • Administer epinephrine, fluid resuscitation, and position the patient appropriately.

    • Monitor and treat with antihistamines and possibly steroids.

Urticaria and Angioedema

  • Urticaria (Hives): Characterized by evanescent, edematous papules lasting less than 24 hours, often caused by food, medications, or infections.

  • Angioedema: Deeper swelling in the skin, frequently associated with urticaria, can be caused by medications or foods.

Adverse Reactions to Food

Food allergies manifesting as cutaneous symptoms or gastrointestinal distress are significant in pediatrics.

  • Classification: IgE-mediated (immediate) and non-IgE-mediated (delayed).

  • Common Reactions: Skin reactions such as urticaria or atopic dermatitis, GI symptoms, and respiratory issues.

  • Management: Identify and eliminate offending foods, and monitor children for tolerance development over time.

Common Pediatric Dermatologic Diseases

Neonatal Skin Conditions

  1. Milia: Small, firm cysts often resolving without treatment.

  2. Dermal Melanocytosis: Also known as Mongolian spots; typically fade during infancy.

  3. Erythema Toxicum: Self-limited rash appearing typically on the second day of life.

Seborrheic Dermatitis

  • Most common in infants characterized by scaly patches often requiring topical antifungal treatments.

Psoriasis

  • Multifractorial skin condition with types like plaque and guttate psoriasis. Treatments may include emollients and corticosteroids.

Impetigo

  • The most common infection in children presenting as crusted lesions with various treatment protocols depending on severity.

SJS/TEN (Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis)

  • Severe mucocutaneous reactions requiring intensive management.

Diaper Candidiasis

  • Involves a characteristic "beefy red" rash with peripheral scaling, treated primarily with antifungal creams.

Scabies

  • Intense itching and burrows on the skin, treated with permethrin and hygiene measures for the entire household.

This outline serves as a comprehensive overview of pediatric dermatology and allergies which may aid in exam preparation.