Dermatology: Part 2

DERMATOLOGY PART 2

INTRODUCTION

• Speaker: Eva Du Vall, MMS, PA-C

• Winter $2026$

• Original slides courtesy of Sara Hughes, MPA, PA-C

LECTURE TOPICS

• Papulosquamous Disorders:

  • Atopic dermatitis

  • Contact dermatitis

  • Lichen planus

  • Lichen simplex chronicus

  • Pityriasis rosea

  • Psoriasis

  • Seborrheic dermatitis

• Vascular Abnormalities:

  • Cherry angioma

  • Telangiectasia

  • Stasis dermatitis

  • Hemangioma

  • Purpura

• Vesiculobullous Diseases:

  • Bullous pemphigoid

  • Pemphigus vulgaris

• Pigment Diseases:

  • Melasma

  • Vitiligo

• Other Dermatologic Disorders:

  • Urticaria

  • Acanthosis nigricans

  • Hidradenitis suppurativa

  • Lipomas

  • Epidermal inclusion cysts

  • Photosensitivity reactions

  • Pilonidal disease

• Desquamation Disorders:

  • Erythema multiforme

  • Stevens-Johnson syndrome

  • Toxic epidermal necrolysis

• Parasitic Infections:

  • Scabies

  • Lice

• Testing Procedures:

  • Indications for photopatch test and patch testing

• Signs Identification:

  • Auspitz sign

  • Nikolsky sign

  • Darier sign

  • Koebner phenomenon

PAPULOSQUAMOUS DISORDERS

ATOPIC DERMATITIS (ECZEMA)

• Definition:

  • Known as "The itch that rashes" with a pathophysiological cycle: itch → scratch → rash → itch → scratch.

• Associations:

  • Skin barrier dysfunction leading to dehydration and IgE reactivity.

  • Potential increase in serum IgE levels, sometimes with eosinophilia present.

• Diagnostic Criteria:

  • Pruritus, characteristic morphology and distribution of lesions, onset during childhood, and chronicity of the condition.

  • Often associated with personal or family history of atopic dermatitis, allergic rhinitis, and asthma (collectively known as atopy).

COMMONLY AFFECTED SITES

• Infants:

  • Face, scalp, extensor surfaces, trunk.

• Toddlers Onward:

  • Flexural surfaces including neck, antecubital (AC) and popliteal fossae, wrists, and ankles.

• Adults:

  • Eyelids in addition to previously mentioned areas.

AGE OF ONSET

• $60\%$ of cases by the first year of life, $30\%$ between ages $2$ to $5$, $10\%$ between ages $6$ to $20$, and rare onset in adulthood.

• For suspected new onset of atopic dermatitis in adults, confirm diagnosis with a dermatologist.

PHYSICAL EXAM

• Acute Presentation:

  • Pruritus, erythema, vesiculation, and weeping.

• Chronic Presentation:

  • Pruritus, xerosis, lichenification, hyperkeratosis (scaling), fissuring, and occasionally hypopigmentation.

EXACERBATING FACTORS

• In infants/children, common triggers include:

  • Eggs, milk, peanuts, soybeans, fish, and wheat.

• Climatic Factors:

  • Condition improves in summer but typically flares in winter.

• Environmental Factors:

  • Aeroallergens specifically dust mites and pollen.

• Other Factors:

  • Wool clothing and emotional stress.

TREATMENT ALGORITHM

• Avoid rubbing and scratching of the affected areas.

• Apply baseline lubrication with emollients (e.g., CeraVe, Vaseline).

• For mild-to-moderate atopic dermatitis:

  • Prolonged topical application of pimecrolimus or tacrolimus combined with emollients.

• For severe flares:

  • Use of topical glucocorticoids (e.g., triamcinolone 0.1\%$3) followed by pimecrolimus or tacrolimus and emollients.

• Consider oral and topical antibiotics to eliminate S. aureus colonization if needed.

• Hydroxyzine can be prescribed to suppress pruritus.

• Consider UVA-UVB phototherapy when indicated.

TOPICAL STEROID POTENCY

• Vehicle Types:

  • Ointment: Most potent and occlusive.

  • Cream: Less potent but preferred for patient comfort due to less residue.

  • Lotion: Less potent, suitable for hairy areas.

  • Gel: Equivalent to lotion but effective for scalp use.

  • Foam: Similar to lotion and gel but typically more expensive.

• Classes of Potency:

  • Class I$: Superpotent steroids.</p></li><li><p>Class$VII$: Least potent steroids.</p></li></ul></li></ul><p>ATOPIC DERMATITIS PEARLS</p><ul><li><p><strong>Corticosteroids Use:</strong></p><ul><li><p>Systemic glucocorticoids should be avoided except for rare instances of severe, intractable disease in adults.</p></li></ul></li><li><p><strong>Moisture Retention:</strong></p><ul><li><p>Apply emollients immediately after bathing to lock in moisture.</p></li></ul></li><li><p><strong>Natural Course:</strong></p><ul><li><p>Spontaneous remission occurs in over$40\%$of childhood cases.</p></li></ul></li></ul><p>CONTACT DERMATITIS</p><ul><li><p><strong>Definition:</strong></p><ul><li><p>Erythema and edema with accompanying pruritus, vesicles, bullae, weeping, or crusting.</p></li></ul></li><li><p><strong>Irritant Contact Dermatitis:</strong></p><ul><li><p>Occurs solely in the area of direct contact with the irritant.</p></li></ul></li><li><p><strong>Allergic Contact Dermatitis:</strong></p><ul><li><p>Extends beyond the area of direct contact with the allergen.</p></li></ul></li></ul><p>IRRITANT CONTACT DERMATITIS</p><ul><li><p><strong>Characteristics:</strong></p><ul><li><p>Sharply demarcated erythema, edema, possible vesicles/bullae.</p></li><li><p>Most commonly found on hands.</p></li><li><p>Can develop within$24$hours post-exposure.</p></li></ul></li><li><p><strong>Common Irritants:</strong></p><ul><li><p>Soaps, detergents, organic solvents.</p></li></ul></li></ul><p>ALLERGIC CONTACT DERMATITIS</p><ul><li><p><strong>Symptoms:</strong></p><ul><li><p>Intense pruritus, erythema, tiny papules/vesicles, weepy or crusted lesions; seldom painful.</p></li><li><p>Involvement beyond contact area, may present with edematous and warm lesions.</p></li><li><p>Symptoms can take$48$hours or more to develop post-exposure.</p></li></ul></li><li><p><strong>Common Allergens:</strong></p><ul><li><p>Poison ivy/oak, topical antibiotics, hair dye, jewelry, rubber products, essential oils, adhesives.</p></li></ul></li></ul><p>CONTACT DERMATITIS TREATMENT</p><ul><li><p><strong>Management Approach:</strong></p><ul><li><p>Identify and eliminate the causative agent.</p></li><li><p>Otherwise, apply wet dressings multiple times a day.</p></li><li><p>Utilize topical glucocorticoids on affected areas.</p></li><li><p>In severe cases, oral steroids like Prednisone at$60\ mg$daily with tapering over$2-3$weeks.</p></li></ul></li><li><p><strong>Prognosis:</strong></p><ul><li><p>Generally good; resolution may take$2-3$weeks depending on causative factors.</p></li></ul></li></ul><p>PATCH TESTING</p><ul><li><p><strong>Purpose:</strong></p><ul><li><p>Document and validate diagnosis of allergic contact sensitization and identify causative agents.</p></li></ul></li><li><p><strong>Procedure:</strong></p><ul><li><p>Test substances are applied to skin within shallow cups (Finn chambers), taped and kept for$24-48$hours.</p></li><li><p>Contact hypersensitivity is indicated by papular vesicular reaction observed within$48-72$hours when the test is assessed.</p></li></ul></li></ul><p>LICHEN PLANUS</p><ul><li><p><strong>Definition:</strong></p><ul><li><p>A pruritic inflammatory disease characterized by four P’s: Pruritic, Purple, Polygonal, Papules/Plaques.</p></li></ul></li><li><p><strong>Demographics:</strong></p><ul><li><p>Most commonly found in middle-aged adults.</p></li></ul></li><li><p><strong>Cardinal Findings:</strong></p><ul><li><p>Classic lichen planus lesions on skin and mucosa; histopathological identification reveals band-like infiltration of lymphocytes in the upper dermis.</p></li></ul></li><li><p><strong>Possible Link to Hepatitis C:</strong></p><ul><li><p>Current studies suggest a correlation.</p></li></ul></li><li><p><strong>Clinical Presentation:</strong></p><ul><li><p>Pruritic, violaceous, flat-topped papules exhibit fine white streaks (Wickham striae).</p></li><li><p>Oral mucosal involvement: Lacy (Wickham striae) or erosive lesions.</p></li><li><p><strong>Koebner Phenomenon:</strong> Appearance of lesions in areas of trauma.</p></li></ul></li><li><p><strong>Risk of Cancer:</strong></p><ul><li><p>Patients with erosive oral/genital lichen planus have up to a$5\%$risk of developing squamous cell carcinoma (SCC).</p></li></ul></li><li><p><strong>Treatment:</strong></p><ul><li><p>Often resolves spontaneously in$1-2$years. High-potency topical steroids are first-line.</p></li></ul></li></ul><p>LICHEN SIMPLEX CHRONICUS</p><ul><li><p>Arises from chronic habitual rubbing and scratching.</p></li><li><p><strong>Presentation:</strong> Solid plaques with lichenification (thickened skin with accentuated markings).</p></li><li><p><strong>Management:</strong> Behavioral change and high-potency topical steroids, often with occlusion.</p></li></ul><p>PITYRIASIS ROSEA</p><ul><li><p><strong>Overview:</strong> Mild acute inflammatory disease likely caused by HHV-$6$or HHV-$7$.</p></li><li><p><strong>Clinical Findings:</strong> Starts with a "herald patch" (initial larger plaque) followed by a generalized eruption of oval salmon-colored plaques in a "Christmas tree" distribution.</p></li><li><p><strong>Treatment:</strong> Self-limiting over$6-12$weeks. Symptomatic relief with topical steroids/antihistamines.</p></li></ul><p>PSORIASIS</p><ul><li><p><strong>Definition:</strong> Chronic inflammatory disorder with genetic components. Triggers include stress, trauma (Koebner), and infections.</p></li><li><p><strong>Types:</strong> Plaque, Guttate (post-strep), Inverse, Palmoplantar, Pustular.</p></li><li><p><strong>Clinical Presentation:</strong> Sharply delineated red plaques with silver-white scaling. <strong>Auspitz sign</strong> (pinpoint bleeding when scale is removed).</p></li><li><p><strong>Treatment:</strong></p><ul><li><p>Localized: Topical steroids and Vitamin D analogs.</p></li><li><p>Severe: UV phototherapy, Methotrexate, TNF inhibitors, or IL-$17$/IL-$23$inhibitors.</p></li></ul></li></ul><p>SEBORRHEIC DERMATITIS</p><ul><li><p><strong>Definition:</strong> Chronic condition in areas with sebaceous gland activity. Associated with <em>Malassezia furfur</em>.</p></li><li><p><strong>Presentation:</strong> Orangish-yellowish greasy scales. Known as "cradle cap" in infants.</p></li><li><p><strong>Treatment:</strong> Ketoconazole cream/shampoo, selenium sulfide, or low-potency steroids.</p></li></ul><h6 id="a4e4dcd6-ea36-4778-b232-03333889528c" data-toc-id="a4e4dcd6-ea36-4778-b232-03333889528c" collapsed="false" seolevelmigrated="true">VASCULAR ABNORMALITIES</h6><p>TELANGIECTASIA</p><ul><li><p><strong>Definition:</strong> Dilated capillaries near the skin surface that are blanchable.</p></li><li><p><strong>Treatment:</strong> Laser or electrosurgery if cosmetic correction is desired.</p></li></ul><p>CHERRY ANGIOMA</p><ul><li><p><strong>Characteristics:</strong> Benign, asymptomatic bright red papules appearing after age$30$.</p></li></ul><p>INFANTILE HEMANGIOMA</p><ul><li><p>Common benign tumor of infancy. Often undergoes spontaneous involution by age$10$. Propranolol may be used for obstructing lesions.</p></li></ul><p>PORT WINE STAIN (NEVUS FLAMMEUS)</p><ul><li><p><strong>Definition:</strong> A permanent capillary malformation present at birth.</p></li><li><p><strong>Clinical Presentation:</strong> Flat, pink to dark red patches that do not regress. Often follow distribution of the trigeminal nerve.</p></li><li><p><strong>Associations:</strong> May be linked to Sturge-Weber syndrome.</p></li></ul><p>STASIS DERMATITIS</p><ul><li><p><strong>Pathophysiology:</strong> Chronic venous insufficiency.</p></li><li><p><strong>Presentation:</strong> Erythema, scaling, and hyperpigmentation (hemosiderin staining) on the lower legs/ankles.</p></li></ul><p>PURPURA</p><ul><li><p>Non-blanchable spots from blood extravasation.</p></li><li><p><strong>Petechiae:</strong>$< 3\ mm$. <strong>Ecchymoses:</strong>$> 1\ cm$$.

  VESICULOBULLOUS DISEASES

  BULLOUS PEMPHIGOID

  • Autoimmune subepidermal blisters (tense bullae). Nikolsky sign is negative. Primarily affects the elderly.

  PEMPHIGUS VULGARIS

  • Autoimmune intraepidermal blisters (flaccid bullae). Nikolsky sign is positive. Often involves oral mucosa; potentially life-threatening.

  PIGMENT DISEASES

  MELASMA

  • Symmetric facial hyperpigmentation triggered by UV or hormones (pregnancy).

  VITILIGO

  • Autoimmune destruction of melanocytes resulting in milky-white depigmented patches.

  OTHER DERMATOLOGIC DISORDERS

  • Urticaria: Pruritic, transient wheals (hives).

  • Acanthosis Nigricans: Velvety hyperpigmentation in folds, linked to insulin resistance.

  • Hidradenitis Suppurativa: Chronic inflammation of apocrine glands; nodules and sinus tracts.

  • Desquamation Disorders: Includes Erythema Multiforme (target lesions) and SJS/TEN (life-threatening skin sloughing/detachment based on BSA percentage).

  DIAGNOSTIC SIGNS

  • Auspitz Sign: Pinpoint bleeding when psoriasis scale is removed.

  • Nikolsky Sign: Epidermis separates with lateral pressure (Pemphigus, TEN).

  • Darier Sign: Wheal formation upon rubbing a lesion (Mastocytosis).

  • Koebner Phenomenon: Lesions appear at sites of trauma (Psoriasis, Lichen Planus).