Clin Med: Eczema and Papulosquamous Diseases

Atopic Dermatitis (Eczema)

A pruritic, chronic inflammatory skin disorder.

Atopic Dermatitis Epidemiology

Usually begins in infancy, affecting approximately 20–30% of children and 2–3% of adults.

Atopic Dermatitis Etiology

Driven by a combination of genetic susceptibility, immune dysregulation, skin barrier dysfunction, and environmental exposures.

FLG Gene Mutation in Atopic Dermatitis

A mutation leading to an impaired skin barrier and increased transepidermal water loss, which increases allergen and bacterial penetration.

Atopic Dermatitis Hallmark Symptom

Intense pruritus (itching).

Atopic Dermatitis Clinical Appearance

Lesions are ill-defined, erythematous (red), scaly patches and plaques; see Lichenification with chronic scratching and Erythema, weeping, and crusting during acute flares; Symptoms commonly worsen in cold weather and dry, low-humidity environments;

Infant distribution of lesions: cheeks, scalp, and extensor surfaces of limbs.

Child/adult distribution of lesions: flexural surfaces (such as inner elbows and knees), neck, wrists, and hands; usually spare the axilla (armpit) and groin areas.

Lichenification

Exaggerated, thickened skin markings caused by chronic, repetitive scratching.

Atopic Dermatitis Diagnosis

A clinical diagnosis requiring the presence of pruritus along with typical lesion morphology, age-specific distribution, and a chronic or relapsing course.

Associated clinical findings: Xerosis (dry skin), early onset (usually before age 5), elevated IgE (helpful but not required), personal or family history of atopic triad, allergic shiners

Atopic Triad

asthma, allergic rhinitis, atopic dermatitis

Atopic Dermatitis First Line Treatment

First Line: Skin care (short, lukewarm baths/showers, mild fragrance-free cleansers, patting skin dry), moisturize (Apply thick, fragrance-free ointments or creams like Vaseline at least twice daily and within 3 minutes of bathing) and avoid triggers (Fragranced products, rough fabrics, harsh detergents, hot water, and dry, low-humidity environments).

Atopic Dermatitis Second Line Treatment (for flares)

Low-potency topical corticosteroids used for the face, eyelids, and skin folds; medium potency is used for the trunk and extremities; high potency is reserved for short courses on severe, thick plaques; non-corticosteroids can be used like Tacrolimus (Protopic) and Crisaborole (Eucrisa 2%)

Tacrolimus (Protopic)

A topical calcineurin inhibitor preferred for the face, eyelids, and skin folds to avoid corticosteroid side effects; carries an FDA boxed warning for malignancy (causal link unestablished); non-corticosteroid option for eczema

Crisaborole (Eucrisa 2%)

A topical phosphodiesterase-4 (PDE4) inhibitor applied twice daily; non-corticosteroid option for eczema

Atopic Dermatitis Systemic Therapy

Treatment indicated for moderate-to-severe disease with inadequate response to topical therapy, extensive body surface area involvement, or significant impact on quality of life.

Treatments: Narrowband UVB Phototherapy, Systemic Corticosteroids (short courses only, only for severe acute flares; chronic use must be avoided due to the risk of rebound flares and adverse effects), Antihistamines (improve sleep during severe pruritus but do not treat the underlying skin inflammation); Oral JAK inhibitors

Narrowband UVB Phototherapy

For atopic Dermatitis; performed in dermatology offices 2–3 times/week to reduce skin inflammation in moderate-to-severe disease when topicals are inadequate.

Atopic Dermatitis Complications

Secondary infections of Staphylococcus aureus (most common, treat with topical or oral antibiotics depending on severity) or herpes simplex virus (dermatologic emergency); is often because eczema is a chronic relapsing disease and though many children improve with age, it is more likely to persist with severe childhood disease, early onset, or coexisting asthma/allergic rhinitis

Eczema Herpeticum

A herpes simplex virus secondary infection to eczema; represents a dermatologic emergency treated with oral or IV acyclovir.

Contact Dermatitis

Inflammatory skin reaction caused by direct contact with an irritant or allergen like Soaps, detergents, frequent hand washing, and acids or alkalis; Caused by a direct toxic effect on the skin; no prior sensitization is required. 80% of cases are irritant contact while about

Allergic Contact Dermatitis (ACD) Pathophysiology

A Type IV (delayed) hypersensitivity reaction that requires prior sensitization; to things like Poison ivy/poison oak, nickel, fragrances, preservatives, rubber/latex, and topical antibiotics

Irritant Contact Dermatitis Presentation

Burning, stinging, or itching erythematous, scaly rash restricted to the area of exposure, usually developing within minutes to hours (up to 24 hours); see more often with Healthcare workers, hairdressers, cleaners, and food service workers due to frequent hand washing and chemical exposure.

Irritant Contact Dermatitis Treatment

Identify and avoid the offending irritant, use frequent emollients/barrier creams, and apply topical corticosteroids for localized inflammation; systemic corticosteroids are only for severe or extensive disease

Lip Licker’s Dermatitis

A perioral variant of irritant contact dermatitis caused by chronic saliva exposure.

Allergic Contact Dermatitis Presentation

Intense pruritus with tiny vesicles, or weepy, crusted lesions occurring 24–72 hours after re-exposure; the affected area often suggests the cause and lesions may spread beyond the original site of contact

Allergic Contact Dermatitis Treatment

Total avoidance of the allergen, topical corticosteroids for localized disease, oral corticosteroids for severe or extensive disease (such as poison ivy), and oral antihistamines to relieve itching; For prevention, can do patch testing if the offending allergen is unclear or the dermatitis is recurrent

Psoriasis

A chronic, immune-mediated inflammatory disease that causes rapid keratinocyte proliferation; can have a genetic predisposition and environmental factors contribute; Common triggers are obesity, smoking, stress, certain medications, and streptococcal infections; long-term it is associated with arthritis and an increased cardiovascular risk

Plaque Psoriasis

The most common psoriasis subtype (~80–90% of cases), presenting with well-demarcated erythematous plaques with silvery scale.

Psoriasis Presentation

Well-demarcated erythematous plaques with silvery scale commonly on the scalp, extensor surfaces of elbows and knees, lumbosacral region, gluteal cleft, palms/soles, and nails; often see nail pitting and onycholysis; Arthritis; look for Koebner Phenomenon and Auspitz sign

onycholysis

separation of the nail from the nail bed

Koebner Phenomenon

The development of new skin lesions at sites of skin trauma (such as scratches, surgical scars, tattoos, sunburn)

Auspitz Sign

Pinpoint bleeding that occurs after peeling away the scale overlying a psoriatic plaque.

Psoriasis Treatment

Depending on severity, treat with emollients and high-potency topical corticosteroids combined with a vitamin D analog (calcipotriene); occlusion (applying topical cream and then wrapping) can be used to treat thick plaques; moderate/severe cases should refer to dermatology for narrowband UVB phototherapy or systemic treatments (but not chronic systemic corticosteroids due to the significant risk of severe, life-threatening rebound flares upon withdrawal)

Prognosis is that most patients achieve good control with modern therapies but it is a chronic relapsing disease; additionally, psoriatic arthritis and cardiovascular disease contribute to long-term morbidity

Scalp Psoriasis Treatment

Coal tar or salicylic acid shampoos, combined with topical corticosteroid solutions, foams, or shampoos.

Inverse Psoriasis

A variant characterized by smooth, shiny erythematous plaques with little or no scale, occurring specifically in skin folds (axillae, groin, inframammary folds).

Guttate Psoriasis

Characterized by numerous small, "drop-like" papules with fine scale, most commonly appearing in children and young adults; frequently triggered by a streptococcal pharyngitis infection.

Pustular Psoriasis

Sterile pustules on erythematous skin that can be localized (palms/soles) or generalized; generalized is a dermatologic emergency.

Erythrodermic Psoriasis

Diffuse, generalized erythema and scaling involving most of the body; can lead to life-threatening temperature instability, dehydration, and infection, representing a dermatologic emergency.

Lichen Planus

An immune-mediated inflammatory disorder where a T-cell-mediated attack targets basal keratinocytes in the skin and mucous membranes typically in adults 30-60 years old and can persist for months to years with recurrences

Lichen Planus Presentation

6 Ps primarily at the flexor wrists, forearms, ankles, oral mucosa, and genitalia; can see wickham striae, Koebner phenomenon, and may be associated with hepatitis C infection and medication-induced reactions; can do a skin biopsy if the visual diagnosis is uncertain.

The 6 Ps of Lichen Planus

Pruritic, Purple, Polygonal, Planar (flat-topped), Papules, and Plaques.

Wickham Striae

Fine, white, lacy lines visible on the surface of Lichen Planus papules or on the oral mucosa.

Oral Lichen Planus

Chronic versions carry a small increased risk of developing squamous cell carcinoma

Lichen Planus Treatment

Lesser cases: High-potency topical corticosteroids or topical tacrolimus (especially for oral or genital lesions)

Extensive cases: Phototherapy, or systemic agents managed by dermatology, including oral retinoids, hydroxychloroquine, or immunosuppressants

Pityriasis Rosea

An acute, self-limited inflammatory skin eruption most commonly affecting teenagers and young adults; Unknown etiology, but strongly thought to be associated with human herpesvirus 6 (HHV-6) or 7 (HHV-7) or vaccine-/medication-induced.

Pityriasis Rosea Presentation

herald patch, christmas tree pattern, Collarette, mild pruritus, and may involve proximal extremities; often confused with tinea corporis (ringworm).

Herald Patch

A single, oval, salmon/fawn-colored plaque with a fine scale that typically precedes the generalized eruption of pityriasis rosea by 1–2 weeks.

Christmas Tree Pattern

The secondary generalized eruption of numerous oval scaly plaques that follow skin cleavage lines along the trunk and proximal extremities.

Collarette Scale

A fine, delicate border of scale ("cigarette paper" scale) characteristically seen on pityriasis rosea lesions.

Pityriasis Rosea Treatment

Typically self-limited (often resolves spontaneously in 6–8 weeks, or up to 3 months, without scarring, recurrence is rare), but can give symptomatic treatment like a low- to medium-potency topical corticosteroids to control pruritus; Select severe cases can get narrowband UVB or short course oral/systemic corticosteroids

Seborrheic Dermatitis

A chronic, relapsing inflammatory dermatitis affecting sebaceous gland-rich areas (scalp, eyebrows, nasolabial folds, ears, chest, and beard area), thought to involve Malassezia yeast, sebum production, and an abnormal inflammatory response; mostly occurring in infants (cradle cap) and adults (late adolescence and older).

Infant Seborrheic Dermatitis ("Cradle Cap")

Thick, greasy yellow scales on the scalp; can involve the face, axillae, and diaper area, and typically resolves spontaneously by 12 months of age.

Adult Seborrheic Dermatitis

Greasy, yellow-white scale on an erythematous base; commonly presents as dandruff on the scalp, eyebrows, nasolabial folds, beard area, and external ears, and may be associated with blepharitis.

Infant Seborrheic Dermatitis Treatment

Baby shampoo combined with gentle brushing, and mineral/baby oil to loosen thick scales before washing but usually self-limiting

Adult Seborrheic Dermatitis Treatment

First line treatment is topical ketoconazole (antifungal) shampoo or cream; can use salicylic acid shampoos/creams to dissolve and clear thick scale, Low-potency topical corticosteroids for flares, or topical calcineurin inhibitors for facebut typically don’t need major medications to treat

Allergic shiners

facial pallor with infraorbital darkening/folds