DERM1

Atopic Dermatitis

• Associated with atopic diseases like asthma and allergic rhinitis, creating the atopic triad.
• Involves type 1 hypersensitivity reactions mediated by IgE and helper T cells (Th2).
• Multifactorial causes include genetic predisposition (e.g., mutations in the filaggrin gene), environmental allergen exposure, and immune dysregulation.
• The Hygiene Hypothesis suggests reduced early childhood exposure to allergens increases susceptibility to atopic diseases.
• Structural abnormalities in the epidermis lead to increased permeability to irritants and allergens.
• More common in childhood, with increasing incidence rates; often improves with age.

Clinical Features of Atopic Dermatitis

• Morphology includes eczematous plaques that are often weeping and intensely itchy.
• Infant lesions commonly appear on the face and extensor surfaces, while older children and adults typically have them in flexural areas (e.g., antecubital and popliteal fossae).
• Associated with conditions like ichthyosis (fish-like scaling) and keratosis pilaris (rough skin), along with Dennie-Morgan lines (fold lines under the eyes due to chronic rubbing).

Management of Atopic Dermatitis

• Education focuses on avoidance of triggers and allergens.
• Skin care involves gentle bathing and application of emollients for hydration.
• Treatment options include topical steroids to reduce inflammation and antihistamines for itch relief.

Differential Diagnosis of Dermatitis

• Distinguish from contact dermatitis caused by allergens (e.g., nickel), which involves type 4 hypersensitivity reactions.

Herpes Simplex Virus (HSV)

• HSV-1 and HSV-2 can both affect genital areas; HSV-1 has become increasingly common for genital herpes.
• Lesions emerge 2-12 days after contact, starting as painful vesicles that evolve into various stages (papules, pustules, ulcers).
• Pregnant women can transmit the virus during delivery; cervical or vaginal involvement may cause severe leukorrhea (genital discharge).
• Differential diagnosis includes distinguishing herpes from candida infections.

Healing and Complications of HSV

• Genital lesions heal in 2-3 weeks, but the virus remains latent in nerve ganglia.
• Complication risks include neonatal herpes, part of the TORCH complex, leading to severe conditions like herpes encephalitis in newborns.

Varicella-Zoster Virus (VZV)

• Reactivation of VZV typically occurs in individuals with a history of chickenpox, presenting as a painful dermatomal rash with vesicles and subsequent crusting.
• Most common in the elderly and those with immunosuppression; diagnosis is often clinical.

Management of Herpes

• Antiviral medications (Acyclovir, Valacyclovir) are most effective when started within 72 hours of rash onset.
• Pain management may involve short-term opioids; steroids don't reduce the risk of post-herpetic neuralgia.

Urticaria (Hives)

• Characterized by rapid onset of wheals and erythema due to IgE-mediated hypersensitivity.
• Histamine release from mast cells results in vasodilation and edema.
• Triggers include food, medications, exercise, temperature changes, vibration, and stress.
• Chronic urticaria is defined as 2-3 episodes per week lasting over 6 weeks.

Melanoma Insights

• Key indicators of concerning moles include the ABCDE criteria: Asymmetry, Border irregularity, Color variegation, Diameter (>6 mm), Evolution.
• Growth patterns involve radial growth (less metastatic risk) and vertical growth (higher metastatic risk).
• Incidence rates indicate 1 in 65 in the U.S.; prognosis is best assessed by depth of invasion.

Melanoma Management

• Complete excision of the primary and metastatic lesions is crucial.
• Sentinel lymph node biopsy is indicated for lesions >0.8 mm or ulcerated lesions.
• Consider adjuvant systemic immunotherapy and preventive measures such as UV protection, including clothing and timely sunblock application.

Differential Diagnosis of Pigmented Lesions

• Atypical nevi may violate ABCDE criteria and require biopsy for confirmation.
• Seborrheic keratosis has a "stuck-on" appearance, often in elderly individuals; associated with GI cancer (Leser-Trélat sign).
• Actinic lentigo occurs from sun exposure, presenting as small, sharply circumscribed pigmented lesions.

General Demographics and Management

• Melanomas occur across all ages but more frequently in individuals with darker skin tones, with peak incidence in early adulthood.
• Management may include topical steroids, UVB light therapy for repigmentation, and camouflage cosmetics for cosmetic purposes.
• Long-term care necessitates ongoing treatment and psychological support due to the impact on self-esteem.