Dermatitis and eczema Notes


Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Dermatitis and eczema essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Dermatitis and eczema:

Atopic dermatitis

Contact dermatitis

Seborrhoeic dermatitis

NOTES NOTES DERMATITIS & ECZEMA GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Inflammatory skin disorders ▪ Immune-mediated skin damage SIGNS & SYMPTOMS ▪ Rashes ▫ Pruritus (itching), burning, pain OTHER DIAGNOSTICS ▪ Rash ▫ Appearance, distribution TREATMENT MEDICATIONS ▪ Corticosteroids ▪ Immunosuppressants DIAGNOSIS LAB RESULTS ▪ Skin biopsy, blood tests ATOPIC DERMATITIS (ECZEMA) ▪ Allergic, inflammatory skin condition ▪ Common for children; may affect adults ▪ Associated with elevated serum IgE levels ▫ Atopy: predisposition to IgE antibody release after trigger exposure Type 4 hypersensitivity ▪ Primary immune dysfunction ▫ T cell subset imbalance → Th2 predominance → increased inflammatory cytokine production (IL-4, 5, 13) → increased release of IgE from plasma B-cells, recruitment of mast cells, eosinophils TYPES RISK FACTORS PATHOLOGY & CAUSES Type 1 hypersensitivity ▪ Epidermal barrier dysfunction ▫ Skin barrier defects (e.g. filaggrin mutation) → antigen entry → inflammatory cytokines 10 OSMOSIS.ORG ▪ Family history of atopy (eczema, asthma, allergic rhinitis) ▪ Environmental allergen sensitivities ▪ Loss of function mutation in filaggrin gene (skin barrier function)
Chapter 2 Dermatitis & Eczema ▪ Higher incidence in urban populations, high-income countries ▪ Low levels of early life exposure to endotoxin (immunogenic component of gram-negative bacteria) COMPLICATIONS ▪ Skin infections ▫ Staphylococcus aureus common commensal organism → impetigo ▪ Eczema herpeticum ▫ Rapid spread of herpes simplex virus on affected skin ▪ Social stigma, anxiety SIGNS & SYMPTOMS ▪ Acute ▫ Pruritic erythematous papules, vesicles with exudate, crusting ▪ Chronic ▫ Dry, excoriated erythematous papules with scaling; lichenification (hyperplasia) ▪ Dry skin ▪ Pruritus → chronic scratching → skin thickening, increased infection risk ▪ Cutaneous hyperreactivity to environmental antigens/stimuli (e.g. stress) ▪ 0–2 years old ▫ Erythematous, pruritic, scaly, crusted lesions +/- vesicles, serous exudate ▫ Extensor surfaces, cheeks, scalp ▪ 2–16 years old ▫ Lichenified plaques (thickened epidermis) ▫ Flexural distribution (e.g. antecubital, popliteal fossae); volar aspect of wrists, ankles, neck ▪ Adults ▫ Localized lichenified plaques ▫ Flexural surface involvement ▫ Uncommonly involves face/neck/hands DIAGNOSIS LAB RESULTS ▪ Elevated level of Serum IgE OTHER DIAGNOSTICS ▪ Morphology, distribution of lesions United Kingdom working group atopic dermatitis criteria ▪ Mandatory ▫ Evidence of pruritic skin with rubbing/ scratching ▪ ≥ three following criteria ▫ Skin crease involvement (antecubital fossa, popliteal fossae, neck, around eyes, ankles) ▫ History/first degree relative with asthma/hay fever ▫ Dry skin in past year ▫ < two years old before symptoms arose (not applicable to children < four years old) ▫ Visible dermatitis of flexural surfaces (< four years old → examine cheeks, forehead, outer aspects of extremities) Figure 2.1 Atopic dermatitis affecting the flexural surfaces of the forearms. TREATMENT MEDICATIONS ▪ Control pruritus ▫ Antihistamines ▫ Topical calcineurin inhibitors (tacrolimus ointment, pimecrolimus cream) ▫ Antibiotics to treat associated skin infections ▪ Immune suppression ▫ Topical → systemic corticosteroids OSMOSIS.ORG 11
▫ Topical calcineurin inhibitors ▫ Oral cyclosporine ▫ Dupilumab (IL-4 receptor antagonist) OTHER INTERVENTIONS ▪ Reduce exposure to environmental allergens ▪ Avoid triggers ▫ Heat, low humidity ▪ Manage stress/anxiety ▪ Maintain skin hydration ▫ Thick, unscented creams with low water content/ointments without water ▫ Apply after bathing/hand washing ▫ Avoid lotions with high water/low oil content (evaporation dries out skin, triggers outbreak) ▪ Control pruritus ▫ Prevent scratching; keep fingernails short (esp. young children) CONTACT DERMATITIS PATHOLOGY & CAUSES ▪ Inflammation of skin after contact exposure to allergens/irritants ▪ Localized ▪ Exposure to foreign substance triggers immune response ▪ Most common form: irritant contact dermatitis CAUSES ▪ Exposure to irritant (irritation may be mechanical/chemical/physical) ▫ Acute: strong irritant ▫ Chronic: recurring exposure to weak irritant ▪ Detergents, surfactants, extreme pH, organic solvents, water ▫ Altered epidermal barrier function: Fat emulsion → defatting of dermal lipids → cellular damage to epithelium → DNA damage, transepidermal water loss → cytotoxic cell damage → cytokine release from keratinocytes → activation of innate immunity ▪ Plants with spines/irritant hairs ▪ Low humidity ▫ Skin loses moisture more easily 12 OSMOSIS.ORG Allergic contact dermatitis ▪ Anacardiaceae family plants ▫ Poison ivy, poison oak, poison sumac ▪ Nickel, fragrances, dyes ▫ Induction phase: immune system primed for allergic response to antigen ▫ Elicitation phase: contact allergens are typically haptens → small, can cross stratum corneum of skin to associate with epidermal proteins → form complete reactive antigen → dendritic cells recognise antigen → internalise antigen, transport to lymph nodes → present to T lymphocytes → trigger immune response → cell mediated immune response (Type IV delayed hypersensitivity) → memory cells remain within skin. Future exposure → triggers memory cells → immune response (cytokines, chemokines, TNF, lymphocytes, granulocytes migrate) RISK FACTORS ▪ Age ▫ Infants: highest risk ▫ > 65 years old: lowest risk ▪ Body site exposure ▫ Difference in thickness of stratum corneum, barrier function ▫ Face, dorsum of hands, finger webs are prone to irritation ▪ Atopy
Chapter 2 Dermatitis & Eczema ▫ Chronically impaired barrier function ▪ Occupational exposure ▫ Continuous moisture exposure, repeated cycles of wet-to-dry from frequent handwashing ▪ Allergic contact dermatitis ▫ Occupation (health professionals, chemical industry, beauticians, hairdressers, machinists, construction) ▫ Increases with age ▫ History of atopic dermatitis SIGNS & SYMPTOMS ▪ Erythematous rash (can develop ≤ 72hrs after exposure) ▪ Vesicles/bullae/wheals occur at exposure site ▪ Glaze/parched/scaled presentation ▪ Scaling, hyperkeratosis, fissuring ▪ Itching (favors allergic etiology); burning (favors irritant) TREATMENT MEDICATIONS ▪ Pruritus ▫ Calamine lotion ▪ Mild topical corticosteroid (hydrocortisone) ▪ Oral antihistamine ▪ Allergic contact dermatitis ▫ High potency topical corticosteroids ▫ Oral corticosteroids ▫ Topical calcineurin inhibitors (tacrolimus/ pimecrolimus) ▫ Systemic immunosuppression (azathioprine, mycophenolate mofetil, cyclosporine) OTHER INTERVENTIONS ▪ Remove/avoid trigger ▪ Treat blistering ▫ Cold compress ▪ Avoid scratching ▪ Retain moisture, protect skin ▫ Barrier cream (e.g. zinc oxide) ▪ Irritant contact dermatitis ▫ Mild acidic solutions (e.g. acetic acid) may neutralize alkali irritants/vice versa ▫ Emollients (e.g. Aquaphor) ▫ Gloves ▪ Allergic contact dermatitis ▫ Phototherapy (narrow band UVB radiation) Figure 2.2 Contact dermatitis secondary to poison ivy exposure. DIAGNOSIS OTHER DIAGNOSTICS ▪ History of possible exposure to irritant/ allergen ▪ Patch allergen testing OSMOSIS.ORG 13
SEBORRHOEIC DERMATITIS PATHOLOGY & CAUSES ▪ Sebaceous gland-centered skin inflammation ▪ Response to fungal antigens/irritants ▪ Chronic/relapsing ▪ Typically mild form of dermatitis CAUSES ▪ Occurs in sites with greater density of sebaceous glands ▪ Not a disease of sebaceous glands, nor increased sebum production ▪ Suspected connection to lipid-dependent fungal genus Malassezia ▫ Immune response to fungus ▫ Local irritants produced by fungus ▪ Children ▫ Nutritional deficiencies of biotin, pyridoxine (vitamin B6), riboflavin (vitamin B2) Distribution ▪ Areas containing significant number of sebaceous glands ▫ External ear, center of face, upper trunk, areas where skin rubs together ▪ Scalp ▫ Infants: aka cradle cap; self-resolving ▫ Adults: aka dandruff (pityriasis sicca); mildest form ▫ Fine, white scaliness without erythema +/- pruritus ▫ Severe cases: inflammation; patchy orange plaques with yellow, oily scales (pityriasis steatoides); may progress to oozing/crusting fissures affecting outer canal, concha of ear (vulnerable to superinfection) ▪ Face ▫ Forehead, eyebrows, glabella, nasolabial folds; may affect cheeks/malar area in butterfly distribution ▫ Frequently affects areas of facial hair distribution RISK FACTORS ▪ Age (biphasic incidence: 2–12 months of age to adolescence; adulthood: peaks 30s–40s) ▪ Hyperandrogenism ▪ Biological males > biological females ▪ HIV ▪ Parkinson’s ▪ Stress ▪ Cold, dry weather ▪ Sleep deprivation ▪ Poor general health SIGNS & SYMPTOMS ▪ Scaling erythematous plaques ▪ Scales yellow, oily in appearance Figure 2.3 Seborrhoeic dermatitis affecting both nasal folds. 14 OSMOSIS.ORG
Chapter 2 Dermatitis & Eczema ▪ Periocular ▫ Blepharitis, free margin redness ▫ Yellow crusting between lashes ▫ Can occur in isolation/part of larger distribution ▪ Trunk (five distinct patterns of distribution) ▫ Moist, skin-contact regions: axillae, inframammary folds, umbilicus, genitocrural ▫ Petaloid pattern: fine, scaling plaques over sternum/interscapular ▫ Annular/arcuate: round, scaly plaques, may have hypopigmented central clearing ▫ Pityriasiform pattern: mimics pityriasis rosea, 5–15mm oval, scaly lesions along lines of skin tension ▫ Psoriasiform pattern: large, rounded erythematous plaques with thick scales DIAGNOSIS OTHER DIAGNOSTICS ▪ History, appearance, distribution TREATMENT MEDICATIONS ▪ ▪ ▪ ▪ ▪ ▪ Topical antifungals Antifungal shampoo Topical corticosteroids Topical calcineurin inhibitors Oral antifungals Antiandrogens ▫ Reserved for individuals for whom feminization/male infertility is unproblematic ▫ Sexually-active, uterus-bearing people: combine with contraception to avoid risk to fetus OTHER INTERVENTIONS ▪ Cradle cap ▫ Apply emollient (petroleum jelly, vegetable oil, baby oil) to scalp overnight to loosen scales → remove scales with soft toothbrush ▫ Frequent shampooing with mild, nonmedicated baby shampoo → remove scales with soft toothbrush ▫ Extensive/persistent cases → medical therapy ▪ Topical ▫ Coal tar shampoo/ointment OSMOSIS.ORG 15

Osmosis High-Yield Notes

This Osmosis High-Yield Note provides an overview of Dermatitis and eczema essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Dermatitis and eczema by visiting the associated Learn Page.