Here are the complete notes in text form:
DERMATITIS – EASY STUDY NOTES
Source: Habif's Clinical Dermatology (Chapters 3, 4, 5)
CHAPTER 3: ECZEMA & HAND DERMATITIS
1. THREE STAGES OF ECZEMA
ACUTE ECZEMA
- Look: Red, swollen, tiny clear vesicles, may blister or ooze
- Feel: Intense itch (even during sleep)
- Examples: Poison ivy, id reaction, pompholyx, acute nummular eczema
- Treatment: Cool wet compresses, oral or intramuscular steroids, topical steroids, antihistamines, antibiotics
SUBACUTE ECZEMA
- Look: Red + scaling, dry, indistinct borders, "parched" or "scalded" appearance
- Feel: Slight to moderate itch, burning, stinging
- Examples: Atopic dermatitis, contact dermatitis, stasis dermatitis, nummular eczema
- Treatment: Topical steroids (with or without occlusion), lubrication, antihistamines, tar; STOP wet dressings at this stage
CHRONIC ECZEMA
- Look: Thick skin, accentuated skin lines = lichenification ("washboard" appearance), excoriations, fissuring
- Feel: Moderate to intense itch
- Examples: Lichen simplex chronicus, atopic dermatitis, hyperkeratotic eczema, chapped fissured feet
- Treatment: Potent topical steroids + occlusion, intralesional steroid injection, antihistamines, lubrication
KEY POINT: Eczema can start at any stage and move to another. Secondary infection converts subacute into acute. Habitual scratching converts subacute into chronic.
2. HAND ECZEMA
Types:
- Irritant contact dermatitis - Most common (35%); "dishpan hands" - Back of hands, fingers
- Atopic hand dermatitis - History of childhood eczema - Back of hands
- Allergic contact dermatitis - Patch test positive; 19% of cases - Varies by allergen
- Pompholyx (dyshidrosis) - Deep-seated vesicles on palms/sides of fingers - Palms, lateral fingers, soles
- Fingertip eczema - Dry, fissured, skin lines disappear - Fingertips only
- Hyperkeratotic eczema - Dense yellow-brown scale, deep cracks - Palms, mainly in middle-aged men
- Nummular eczema - Coin-shaped plaques - Back of hands
- Recurrent focal palmar peeling - Noninflammatory peeling in summer - Palms and soles
IRRITANT CONTACT DERMATITIS (Most Common Hand Eczema)
Mechanism: Stratum corneum is damaged by repeated irritants and the skin barrier breaks down.
Who gets it: Mothers with young children (diaper changing), hairdressers, dishwashers, surgeons, dentists, bartenders, fishermen, industrial workers.
Progression: Dryness and chapping → cracks and fissures (especially over joint creases and fingertips) → red swollen backs of hands → vesicles and oozing → (if caustic chemical) necrosis and ulceration.
Patient Instructions:
- Wash hands as infrequently as possible; use lukewarm water only
- Shampoo with rubber gloves or have someone else do it
- Avoid direct contact with household cleaners and detergents
- Wear white cotton gloves under unlined rubber gloves
Treatment: Treat by stage (acute/subacute/chronic). Lubrication is essential. Use barrier creams applied at least twice daily on all exposed areas.
ATOPIC HAND DERMATITIS
- Most common form of adult atopic dermatitis
- Starts as irritant chapping and erythema on back of hands
- Predictors: Hand dermatitis before age 15, persistent eczema on body, dry or itchy skin in adult life, widespread childhood atopic dermatitis
- Treatment: Same as irritant hand eczema - avoid irritants and lubricate frequently
ALLERGIC CONTACT DERMATITIS (Hands)
Common allergens:
- Nickel (door knobs, scissors, jewelry, knitting needles)
- Potassium dichromate (cement, leather gloves)
- Rubber (gloves, industrial equipment)
- Fragrances (cosmetics, soaps, topical medications)
- Formaldehyde (wash-and-wear fabrics, cosmetics)
- Lanolin (topical lubricants and medications)
Diagnosis: Patch testing confirms the allergen.
Treatment: Identify and avoid the allergen; treat active eczema as subacute or chronic.
POMPHOLYX (DYSHIDROSIS)
- Symmetric vesicular hand and foot dermatitis of unknown cause
- Intense itching precedes vesicles on palms and sides of fingers
- Palms are red and wet with perspiration (hence "dyshidrosis" - but NOT actually related to sweat glands)
- Vesicles resolve in 3-4 weeks, replaced by rings of scale
- Pain rather than itch is the chief complaint in chronic cases
- Causes: Allergic contact (67.5%), mycosis (10%), idiopathic atopic (15%)
- Nickel, cobalt, and chromium ingestion can trigger it even if patch test is negative
Treatment:
- Topical steroids + cool wet compresses (first-line)
- Oral antibiotics if secondary infection
- Short courses of oral steroids for acute flares
- PUVA therapy for resistant cases
- Low-dose methotrexate (15-22.5 mg/week) for debilitating cases unresponsive to steroids
- Oxybutynin (anticholinergic) may help through its effect on hyperhidrosis
- Low-nickel diet if metal-sensitive (64% of patients on diet cleared or markedly improved)
FINGERTIP ECZEMA
- Dry, cracked, fissured, tender fingertips; skin lines are lost
- Skin peels from fingertip distally; stops before distal interphalangeal joint
- Cause: Contact allergy (plant bulbs, resins) or unknown
- Chronic and resistant to treatment
Treatment:
- Rule out allergy and psoriasis first
- Avoid irritants and lubricate frequently
- Topical steroids with or without occlusion give only temporary relief
- Try pimecrolimus, tacrolimus, crisaborole, or tar creams twice daily
HYPERKERATOTIC ECZEMA
- Almost exclusively in men (middle-aged and elderly)
- Dense yellow-brown scale on palms that forms deep interconnecting cracks "like mud drying in a riverbed"
- Scale is moist below the surface; peeling it away causes bleeding
- Cause usually unknown; may result from allergy or irritation
Treatment:
- Group II topical steroid cream + occlusion
- Recurrences are frequent
- Patch test if recurrent
NUMMULAR ECZEMA (Coin-shaped)
- Round, coin-shaped (1-5 cm) eczematous plaques
- Common in middle-aged and elderly; unknown cause
- Back of hands most common site; also extensor forearms and legs, flanks, hips
- Vesicles may appear on the plaque surface
- Chronic with variable course; some cases resolve, others persist for years
Treatment:
- Based on stage of inflammation
- Acute (vesicular): treat as acute eczema
- Red scaling plaques: treat as subacute eczema
- Thick, scratched plaques: treat as chronic eczema
- Tacrolimus ointment 0.1% used alone or intermittently with topical steroids
RECURRENT FOCAL PALMAR PEELING
- Non-inflammatory, bilateral peeling of palms (occasionally soles)
- Most common in summer; associated with sweaty palms
- Scaling starts from several points, extends peripherally; central area becomes slightly red and tender
- Asymptomatic; chronic and recurrent
- Resolves in 1-3 weeks; requires no therapy other than lubrication
3. OTHER ECZEMA PRESENTATIONS
ASTEATOTIC ECZEMA (Eczema Craquelé)
- Occurs after excess drying, especially in winter and among the elderly
- Atopic patients are more likely to develop this pattern
- Most common on anterolateral aspects of lower legs
- Look: "Cracked porcelain" or "crazy paving" pattern - long horizontal fissures connect with short vertical fissures
- Pain rather than itching is the chief complaint in severe cases
- Scratching or using drying lotions (calamine) makes it much worse
Associated conditions: Malignancy (lymphoma, leukemia, solid organ tumors), malnutrition, anorexia nervosa, Sjögren syndrome, chronic graft-versus-host disease, CHF, nephrotic syndrome, cirrhosis, retinoids use.
Treatment:
- Initial/mild stages: Group III or IV topical steroid ointments (treat as subacute eczema)
- Severe form: Wet compresses + antibiotics first to remove crust and suppress infection, THEN Group V topical steroids + lubricants
- Wet compresses only for 1-2 days (prolonged use causes excessive drying)
- Lubrication during and after topical steroid use is essential
- AVOID oral steroids - disease flares within 1-2 days after stopping them
CHAPPED FISSURED FEET (Sweaty Sock Dermatitis / Juvenile Plantar Dermatosis)
- Age of onset: Mean 7.3 years; mean remission at 14.3 years (disappears around puberty)
- Cause: Moist socks kept in contact with soles inside impermeable shoes = artificial intertrigo
- Look: Scaling, erythema, fissuring, and loss of epidermal ridge pattern; starts on toes and metatarsal regions; entire sole may be involved
- Worsens throughout winter; clears in late spring; predictably recurs in fall
- Complaint: Soreness and pain (NOT itch like atopic dermatitis of the feet)
Differential Diagnosis:
- Psoriasis: darker red, scales shed (in chapped feet, scales are adherent and removal causes bleeding)
- Tinea pedis: rare in children; fissuring is minimal; little seasonal variation
- Allergic contact dermatitis: affects dorsal aspect; spares soles; bright red and scaly rather than pale red and chapped
Treatment:
- Group II or III topical steroids twice daily (or with plastic wrap occlusion at bedtime)
- Tacrolimus ointment may be effective
- Lubricating creams applied several times daily, especially directly after removing moist socks
- Prevention: Change into light leather shoes after removing boots at school; change cotton socks 1-2 times daily
4. SELF-INFLICTED DERMATOSES
LICHEN SIMPLEX CHRONICUS (LSC / Circumscribed Neurodermatitis)
- Created and perpetuated by habitual scratching of a single localized area
- More common in adults; patients derive pleasure from scratching
- Look: Red, scaly, THICK plaque with ACCENTUATED skin lines (lichenification); well-defined border
- Usually just one lesion; stays localized; does not enlarge significantly
- The disease is self-perpetuating: scratching → thickening → more itch → more scratching
Sites (in order of frequency):
- Outer lower portion of lower leg
- Scrotum, vulva, anal area, pubis
- Wrists and ankles
- Upper eyelids
- Back and side of neck (lichen simplex nuchae - almost exclusively women)
- Orifice of the ear
- Extensor forearms near elbow
- Fold behind the ear
- Scalp (picker's nodules)
Treatment:
- FIRST: Explain to patient that the rash will not clear until all scratching and rubbing is stopped
- Cover the area at night if scratching occurs during sleep
- Topical steroids: Clobetasol is very effective for neck, legs, wrists, ankles, and vulva
- Intertriginous areas (anal, fold behind ear): Group V or VI steroids only (not potent steroids)
- Lichen simplex nuchae (back of neck) - difficult to treat; fluocinonide applied twice daily for scalp extension
- Intralesional triamcinolone acetonide 10 mg/mL - very effective; may give monthly
- Cordran tape (occlusive steroid tape)
- Oral antibiotics if secondarily infected
PRURIGO NODULARIS
- Nodular form of lichen simplex chronicus; intractable pruritus
- Look: Few to 20+ nodules, 1-2 cm, hard, dome-shaped, smooth or warty or crusted surface
- Location: Extensor aspects of arms and legs (randomly distributed)
- Neural hyperplasia is a constant feature
- Resistant to treatment; lasts for years
Evidence-Based Treatments:
TOPICAL:
- Betamethasone 0.1% ointment: Twice daily with occlusion; alternate with steroid-sparing agents
- Calcipotriol 50 mcg/g ointment: Twice daily; may be more efficacious than betamethasone
- Pimecrolimus 1% cream: Twice daily; discuss FDA black-box warning with patient
- Tacrolimus 0.1% ointment: Twice daily; discuss FDA black-box warning
- Capsaicin 0.025%-0.3%: Apply 4-6 times daily; high application frequency leads to low compliance; gradual healing over months
ORAL:
- Fexofenadine (240 mg twice daily) + Montelukast (10 mg daily): Reduces pruritus
- Naltrexone 50 mg/day: Opioid antagonist; 41% exacerbation rate after stopping
- Gabapentin 900 mg/day for 3-4 months; taper to 300-600 mg/day for maintenance
- Pregabalin 25 mg 3 times/day for 3 months; taper to 50 mg/day; more efficacious than antihistamines
- Cyclosporine 3-5 mg/kg/day: Effective in studies
- Thalidomide and lenalidomide: For most recalcitrant cases; REQUIRE special registry (embryo-fetal toxicity)
PROCEDURAL:
- Intralesional triamcinolone acetonide 10 mg/mL injections: Very effective; give monthly
- Cryotherapy: Sometimes successful
- Excision of individual nodules: Sometimes helpful
NEUROTIC EXCORIATIONS
- Patient-induced linear excoriations; most patients aware they create the lesions
- Psychiatric associations: OCD, perfectionistic and compulsive traits, depression, anxiety, somatoform disorders
- Look: Few to several hundred excoriations in easily reached areas; face is most common site; also extensor arms and legs, abdomen, thighs, upper back and shoulders
- Groups of white scars surrounded by brown hyperpigmentation are characteristic
Treatment:
- Group I topical steroids twice daily OR Group V under plastic wrap occlusion
- Systemic antibiotics
- Intralesional triamcinolone acetonide 10 mg/mL for resistant lesions
- Frequent lubrication; encourage substituting lubricant application ritual for the digging ritual
- Empathic, supportive approach (significantly more effective than insight-oriented psychotherapy)
- Antidepressants (SSRIs, SSNRIs, TCAs) for depression
- Behavioral therapy for OCD
- Psychiatric referral if supportive approach fails
PSYCHOGENIC PARASITOSIS (Delusional Infestation)
- Conviction that skin is infested with organisms despite no objective evidence
- Mostly female, long history of symptoms, disabled or retired, seen at many centers
- "Matchbox sign": Patient brings skin debris, dried blood, fibers, or "insects" in matchboxes as proof
- Patients describe infestation with insects, worms, fibers - almost half report multiple entities
Management:
- Rule out true infestation (scabies, animal/bird mites can actually be present)
- Listen and show concern; examine skin with magnification; prepare scrapings
- Do NOT suggest the diagnosis is obvious on first visit
- Collect specimens brought by patient; set them aside for later evaluation
- If belief is shakable: Offer benzodiazepine for anxiety + suggest psychiatric referral at 2-week follow-up
- If belief is unshakable (true delusional disorder): Antipsychotics - Pimozide (Orap), Risperidone (Risperdal), Olanzapine (Zyprexa), or Quetiapine (Seroquel)
- Antidepressants may be added for comorbid depressive disease
5. STASIS DERMATITIS AND VENOUS ULCERS
STASIS DERMATITIS
Cause: Venous insufficiency → increased hydrostatic pressure → eczematous eruption on lower legs. Occurs over medial malleolus most commonly.
Three Stages:
SUBACUTE INFLAMMATION:
- Usually begins in winter; legs become dry and scaly
- Brown staining of skin = hemosiderin (iron remaining from disintegrated RBCs that leaked from veins)
- Treatment: Group II-V topical steroid creams/ointments + lubricating creams/lotions
ACUTE INFLAMMATION:
- Sudden red, superficial itchy plaque on lower leg
- May have weeping, crusts, fissuring
- May trigger id reaction (vesicular eruption) on palms, trunk, or extremities
- Treatment: Oral anti-Staph antibiotics (cephalexin) + tepid wet compresses + Group III-V topical steroids
- Id reaction resolves spontaneously as primary site improves
CHRONIC INFLAMMATION:
- Cyanotic red plaque over medial malleolus
- Fibrosis → permanent skin thickening; cobblestone/bumpy appearance
- Skin remains thickened and diffusely dark brown (postinflammatory hyperpigmentation) during quiet periods
- Treatment: Topical steroids; treat underlying venous disease; compression
IMPORTANT RULES FOR STASIS DERMATITIS:
- NEVER apply steroid creams directly onto the ulcer - it stops the healing process
- ALWAYS elevate the legs
- AVOID neomycin, parabens, and lanolin in topical products - high sensitization risk in venous skin
- Patch test if inflammation persists after appropriate treatment
VENOUS LEG ULCERS
THREE TYPES OF LEG ULCERS COMPARED:
VENOUS ULCER:
- Location: Medial malleolus
- Appearance: Shallow, irregular borders; base develops granulation tissue
- Pain: Dull; IMPROVES with leg elevation
- Exam: Varicose veins, leg edema, dermatitis, skin thickening
- ABI: Greater than 0.9 (normal)
- Risk factors: DVT, obesity, significant leg injury
- Treatment: Compression therapy + leg elevation (cornerstone)
ARTERIAL ULCER:
- Location: Distal, over bony prominences
- Appearance: Round, punched-out, well-demarcated; fibrinous yellow base or necrotic eschar
- Pain: Severe; does NOT improve with elevation
- Exam: Absent or decreased pulses, shiny atrophic skin, no hair, dystrophic toenails
- ABI: Less than 0.7
- Risk factors: Diabetes, hypertension, smoking, hypercholesterolemia
- Treatment: Pentoxifylline, vascular surgery assessment; patient must quit smoking
NEUROPATHIC ULCER:
- Location: Pressure points on feet (metatarsal head, heel, junction of hallux and plantar surface)
- Appearance: Callus surrounding wound, undermined edges, bone/tendon exposure possible
- Pain: Foot numbness, burning, paresthesia (patient may feel nothing)
- Exam: No sensation to monofilament, Charcot joints, claw toes
- ABI: Normal
- Risk factors: Diabetes, leprosy, frostbite
- Treatment: Vigorous surgical debridement; pressure avoidance; custom-molded shoes
TREATMENT OF VENOUS ULCERS
Step 1 - Reduce venous pressure and edema: Bed rest, leg elevation, compression bandages/stockings
Step 2 - Control surrounding inflammation: Tepid wet Burow's solution compresses (30-60 min, several times/day) + Group V topical steroids applied 2-4 times/day
Step 3 - Treat infection: Systemic antibiotics (anti-Staph: cephalexin); topical antibiotics (Iodoflex pad, Iodosorb gel); Silver nitrate 0.5% compresses preferred when infection present
Step 4 - Debride ulcer bed: Enzyme-debriding agents; surgical or mechanical debridement; replace compresses hourly for first 24-72 hours to debride
Step 5 - Use appropriate dressings: Occlusive dressings promote rapid healing and wound debridement
Step 6 - COMPRESSION is the cornerstone:
- Check Ankle-Brachial Index (ABI) BEFORE applying compression
- ABI 0.8-1.2: High compression therapy
- ABI 0.5-0.8: Modified compression (maximum 20 mmHg)
- ABI less than 0.5: NO compression (contraindicated)
- During healing: Compression bandages
- After healing: Graded compression stockings to prevent recurrence
Compression Stocking Classes:
- Class I (20-30 mmHg): Mild edema, varicose veins
- Class II (30-40 mmHg): Moderate edema and venous disease
- Class III (40-50 mmHg): Severe edema, severe venous disease, lymphedema
- Class IV (50-60 mmHg): Lymphedema
Step 7 - Additional treatments: Pentoxifylline 400-800 mg three times daily (improves healing by 50%), doxycycline (antiinflammatory), vitamins C and E + zinc, flavonoids, low-molecular-weight heparin, sulodexide
Difficult/non-healing cases: Skin grafts, bioengineered skin, growth factors, electrostimulation, negative pressure wound therapy
CHAPTER 4: CONTACT DERMATITIS & PATCH TESTING
6. IRRITANT vs. ALLERGIC CONTACT DERMATITIS
IRRITANT CONTACT DERMATITIS:
- Who gets it: Everyone (no genetic predisposition needed)
- Mechanism: Nonimmunologic; physical and chemical alteration of epidermis
- Number of exposures: Few to many (depends on individual's barrier integrity)
- Nature of substance: Organic solvents, alkaline soaps
- Concentration required: Usually high
- Onset: Usually gradual as epidermal barrier becomes compromised
- Distribution: Borders usually indistinct; confined to area of contact
- Diagnosis: Trial of avoidance
- Management: Protection and reduced exposure
ALLERGIC CONTACT DERMATITIS:
- Who gets it: Only genetically predisposed individuals
- Mechanism: Delayed hypersensitivity (Type IV); T-cell mediated
- Number of exposures: One or several to cause sensitization; then rapid (12-48 hours) on re-exposure
- Nature of substance: Low-molecular-weight hapten (metals, formalin, epoxy resins)
- Concentration required: May be very low
- Onset: 12-48 hours after re-exposure once sensitized
- Distribution: May correspond exactly to contactant (watchband, elastic waistband); may spread beyond
- Diagnosis: Trial of avoidance + patch testing
- Management: Complete avoidance of allergen
Management of Irritant Contact Dermatitis:
- Avoid exposure to irritants using protective equipment (gloves)
- Topical steroids for initial inflammation control (some experts say avoid; may compromise barrier)
- Moisturizers used generously and frequently (lipid-rich moisturizers both prevent and treat)
- Barrier creams containing dimethicone or perfluoropolyethers; cotton liners
- Cool compresses for acute inflammation; suppress vesiculation and decrease inflammation
- Wash hands in cool or tepid water only
- Repeated low-level UV exposures may be effective for long-term resistant cases
- Barrier function takes approximately 4 months or more to normalize even after skin appears normal
7. RHUS DERMATITIS (POISON IVY / POISON OAK / POISON SUMAC)
- Most common cause of allergic contact dermatitis in the United States
- Allergen: URUSHIOL (resinous sap; mixture of catechols)
- Found in all parts of the plant including roots and stems in fall and winter
- Hallmark sign: LINEAR vesicular eruption (plant or oleoresin dragged across skin during scratching)
- Blister fluid does NOT contain oleoresin and CANNOT spread the inflammation (common myth)
Cross-reacts with: Cashew nut shells (cashew nut oil is chemically related to urushiol), mango trees, Japanese lacquer trees, ginkgo
Clinical presentation:
- Appearance varies with quantity of oleoresin contact
- Small amounts: erythema only
- Large amounts: intense vesiculation
- Eruption appears 8 hours to 1 week after contact
- Later-appearing lesions are NOT from spreading blisters - they are from smaller amounts of allergen that are slower to evolve
Prevention:
- Washing with any type of soap inactivates and removes all surface oleoresin
- Within 10 minutes: ALL oleoresin can be removed
- After 10 minutes: Only 50% can be removed
- After 30 minutes: Only 10% can be removed
- After 60 minutes: None can be removed (too late)
- IvyBlock (5% quaternium-18 bentonite lotion): Prevents dermatitis in more than 50% of sensitized patients
Treatment:
MILD (erythema only):
- Cool wet compresses 15-30 min, several times daily for 1-3 days
- Topical steroids Group I-V creams or gels, applied 2-4 times daily
- Calamine lotion (controls itch but prolonged use causes drying)
- Hydroxyzine and diphenhydramine for itch and sleep
SEVERE (widespread blistering):
- Prednisone: 60 mg/day on days 1-4, then taper every 2 days by 10 mg, over 14 days total
- Alternative: 20 mg twice daily for at least 7 days; tapering after this short course is usually NOT necessary
- Non-compliant patients: Triamcinolone acetonide 40 mg intramuscularly
- AVOID commercially available steroid dose packs (Medrol Dosepak) - they provide inadequate medication and cause rebound dermatitis
Diagnosis: Usually obvious. Patch testing is NOT done (high risk of inducing sensitization).
8. NATURAL RUBBER LATEX (NRL) ALLERGY
High-risk groups: Healthcare workers, rubber industry workers, persons with multiple surgeries
Three Types of Reactions:
TYPE 1 - IRRITANT CONTACT DERMATITIS:
- Mechanism: Nonimmune; caused by moisture, heat, and friction under gloves
- Presentation: Eczema under gloves
- Treatment: Change gloves type; cool air dry hands
TYPE 2 - ALLERGIC CONTACT DERMATITIS (Type IV):
- Mechanism: T-cell mediated; allergens are rubber accelerators - thiurams (72%), carbamates (25%), mercapto compounds (3%)
- Presentation: Eczema limited to direct contact area (back of hand)
- Diagnosis: Patch testing
- Treatment: Identify allergen by patch testing; use alternative rubber articles without those chemicals; Elastyren or Tactylon hypoallergenic surgical gloves for surgeons
TYPE 3 - IMMEDIATE HYPERSENSITIVITY (Type I, IgE-mediated):
- Mechanism: IgE-mediated; allergens are latex PROTEINS (not rubber chemicals)
- Presentation: Contact urticaria; inhalation causes rhinitis, conjunctivitis, asthma; intraoperative anaphylaxis and death possible
- Cross-reacts with foods: Banana, avocado, tomato, kiwi
- Diagnosis: RAST test first; if negative, supervised "use test" with one glove finger, then whole hand; if still negative, skin-prick test (have life support available)
- Treatment: Nonlatex alternatives; latex-safe hospital environment; powder-free low-allergen gloves for other healthcare workers at the same site
9. SHOE ALLERGY
- Look: Subacute eczema over dorsa of feet; interdigital spaces are SPARED (unlike tinea pedis which involves interdigital spaces)
- Usually bilateral; pale red and chapped rather than bright red
- Most common allergens: Rubber/mercaptobenzothiazole (most common), chromate (leather tanning), p-tert-butylphenol formaldehyde resin (shoe glue)
- These chemicals are leached out by sweat
Diagnosis: Patch testing required. Cut a 1-inch square piece from the shoe, separate glued layers, moisten each layer, and apply to upper outer arm.
Treatment:
- Control perspiration: Aluminum chloride hexahydrate 20% (Drysol) applied at bedtime
- Change socks at least once daily
- Insert barrier insoles (Dr. Scholl's Air Foam Pads)
- Most vinyl shoes are safe substitutes for rubber-sensitive and chrome-sensitive patients
10. METAL DERMATITIS
NICKEL
- Number 1 cause of allergic contact dermatitis worldwide
- Women affected much more frequently than men (men usually sensitized industrially)
- Ear piercing is the most common cause of sensitization
- Classic sites: Earlobes (earrings), wrist (watchband), abdomen (belt buckle), fingers (rings)
- Sources: Jewelry, jean buttons and zippers, scissors, door handles, watchbands, bracelets, belt buckles, keys, hair curlers, coined money (cashiers at risk)
Low-Nickel Diet (for pompholyx or hand eczema in nickel-sensitive patients):
AVOID (HIGH NICKEL): Dark chocolate, cocoa powder, licorice, hazel nuts, almonds, peanuts, walnuts, pistachios, brown beans, soybeans, chickpeas, oatmeal, wheat bran, oat bran, mussels, oysters, shellfish, herring, all canned foods
ALLOWED (LOW NICKEL): All meats, poultry, eggs, milk, yogurt, butter, cheese, polished rice, refined wheat flour, potatoes, cabbage, carrots, cucumbers, lettuce, most fresh fruits (except pears), coffee, wine, beer
COOKING TIP: Do not cook acidic foods in stainless-steel utensils (nickel leaches out)
Baboon Syndrome: Systemic nickel ingestion in sensitized person → symmetric eczema on elbows, axillae, eyelids, sides of neck + bright red anogenital lesions (resembles baboon's red gluteal region)
CHROMATES
- Most common sensitizer in men in industrialized countries
- Sources: Cement (most common cause), leather gloves, shoes, photographic processes, metal, dyes
- Cement acts both as an irritant (strong alkali, pH 12 → chemical burns) and as a sensitizer
- Deep burns occur when cement spills over boot tops and is held against skin
- Workers sensitized to cement chromates develop eczema on backs of hands and forearms that does not respond to steroids until removed from cement exposure
MERCURY
- Mercury in dental amalgam (fillings) does NOT contain nickel
- Allergy to mercury is very rare; patch testing unreliable and rarely done
11. PATCH TESTING
When to use: Suspected contact dermatitis, persistent or recurring eczema unresponsive to standard treatment, unusual eczema, to confirm allergic vs. irritant
T.R.U.E. TEST: 36 allergens in 3 panels applied to the back for 48 hours; detects up to 80% of common allergic contact dermatitis
Reading times:
- First reading: 48 hours after application
- Second reading: 3-7 days after application (important - delayed reactions common especially with neomycin, which may not appear until day 7)
- Extended reading at day 6-7 is recommended especially for older women
Grading:
- (+): Weak positive - erythema, infiltration, possibly papules (nonvesicular)
- (++): Strong positive - edema or vesicular reaction
- (+++): Extreme positive - spreading, bullous, or ulcerative reaction
- IR: Irritant reaction (deep erythema like a burn) - NOT a positive allergy test
- NT: Not tested
Strong ALLERGIC reactions: Vesicular; may spread beyond test site
Strong IRRITANT reactions: Deep erythema resembling a burn; does NOT spread
When NOT to patch test:
- Active, flaring dermatitis covering more than 25% of body surface area ("angry back syndrome" = many false positives)
- Patient recently treated with systemic corticosteroids (wait at least 2 weeks)
- After PUVA or UV phototherapy (wait 1-2 weeks)
- Prednisone 15 mg/day or more may inhibit patch test reactions
Top 15 Allergens (North American Contact Dermatitis Group 2013-2014):
- Nickel sulfate (20.1%)
- Fragrance mix (11.9%)
- Methylisothiazolinone (10.9%)
- Neomycin (8.4%)
- Bacitracin (7.4%)
- Cobalt chloride (7.4%)
- Myroxylon pereirae/Balsam of Peru (7.2%)
- p-Phenylenediamine (7.0%)
- Formaldehyde (7.0%)
- MCI/MI - Cl+Me-isothiazolinone (6.4%)
CHAPTER 5: ATOPIC DERMATITIS (AD)
12. ATOPIC DERMATITIS - OVERVIEW
- Chronic, pruritic, relapsing inflammatory skin disease
- Most common in children; affects 15-25% of children and 7.2% of adults in the USA
- The increase in prevalence is thought to be due to changes in microbe exposure during infancy and childhood
- 45% of AD begins in first 6 months of life; 85% begins before age 5
- Associated with elevated serum IgE levels and personal or family history of hay fever, asthma, very dry skin
- Atopic eczema is synonymous with AD
Atopic Triad: EAR = Eczema + Asthma + allergic Rhinitis
Genetics:
- Polygenic inheritance; 77% concordance in monozygotic twins vs 15% in dizygotic twins
- Multiple genes interact with environment to determine incidence and course
- Filaggrin (FLG) gene mutation is key - present in extrinsic AD
Intrinsic AD:
- Normal IgE levels; no filaggrin mutations
- Begins in adulthood
- TH-17 and TH-22 immune activation
Extrinsic AD:
- Elevated IgE, filaggrin mutations, early onset
- TH-2 dominant immune response
Key Pathology: Filaggrin mutation → decreased skin barrier → reduced microbiome diversity → Staphylococcus aureus colonization (dominant clonal strains in severe disease) → TH-2 cytokine overexpression (IL-4, IL-5, IL-13) → reduced antimicrobial peptides → more S. aureus → more inflammation (vicious cycle)
Course and Prognosis:
- More than 50% of young children with generalized AD develop asthma and allergic rhinitis by age 13
- Up to 80% of children show improvement before age 8 but many continue into adulthood
- 58% of infants with AD still have inflammation 15-17 years later
- Notion that children "outgrow" AD should be abandoned
Unfavorable prognostic factors (in order of importance):
- Persistent dry or itchy skin in adult life
- Widespread dermatitis in childhood
- Associated allergic rhinitis
- Family history of atopic dermatitis
- Associated bronchial asthma
- Female gender
13. CLINICAL PHASES OF AD
INFANT PHASE (Birth to 2 Years)
- Infants rarely born with AD; typically develop first signs around the 3rd month of life
- Most common: Red, scaling plaques on CHEEKS, SPARING perioral and paranasal areas
- Chin often involved due to drooling and repeated washing
- Habitual lip licking → oozing, crusting, scaling on lips and perioral skin
- DIAPER AREA IS OFTEN SPARED (protected from scratching)
- Scalp may be involved (can resemble seborrheic dermatitis)
- Prolonged disease with discomfort disturbs sleep; both parents and child are distraught
- Resolves in approximately 50% of infants by 18 months; others progress to childhood phase
CHILDHOOD PHASE (2 to 12 Years)
- Most characteristic pattern: Inflammation in FLEXURAL AREAS
- Antecubital and popliteal fossae, neck, wrists, and ankles
- Perspiration from exertion → burning and intense itching in these areas → itch-scratch cycle
- Tight clothing trapping heat makes it worse
- Lichenification develops with repeated scratching
- Constant scratching → destruction of melanocytes → areas of hypopigmentation (fade with time)
- Most patients in remission by age 30; a few have lifelong disease
ADULT PHASE (12 Years to Adult)
- Resurgence at puberty (possibly hormonal changes or stress)
- Most common pattern: Localized lichenification
- Common adult patterns:
- Flexural inflammation (same as childhood)
- Hand dermatitis (most common adult expression of atopic diathesis)
- Inflammation around eyes/upper eyelids (patient rubs with back of hand)
- Lichenification of anogenital area (vulva, scrotum, rectum - resistant to treatment; lasts for years)
- Pigmentary alterations (hypopigmentation) may be distressing
14. DIAGNOSTIC FEATURES OF ATOPIC DERMATITIS
Essential (must be present):
- Pruritus
- Eczema with typical age-appropriate pattern:
- Infants: Facial, neck, and extensor involvement
- Children and adults: Flexural lesions
- Sparing of groin and axillary regions
Important supporting features:
- Early age of onset
- Atopy: personal or family history + IgE reactivity
- Xerosis (dry skin)
Associated features (suggest but not diagnostic):
- Atypical vascular responses (facial pallor, white dermographism)
- Keratosis pilaris, ichthyosis vulgaris, hyperlinear palms
- Ocular/periorbital changes
- Dennie-Morgan infraorbital fold (extra line under lower eyelid)
- Perifollicular accentuation, lichenification, prurigo lesions
Conditions to exclude: Scabies, seborrheic dermatitis, contact dermatitis (irritant or allergic), ichthyoses, cutaneous T-cell lymphoma, psoriasis, photosensitivity dermatoses, immune deficiency diseases
15. TRIGGERING FACTORS FOR AD
TEMPERATURE CHANGE AND SWEATING:
- Atopic patients do not tolerate sudden temperature changes
- Sweating induces itching particularly in antecubital and popliteal fossae
- Lying under warm blankets, entering a warm room, physical stress all intensify desire to scratch
- Hot showers temporarily relieve itching (pain better tolerated than itch) but heat aggravates eczema
- Discourage heat-trapping clothing
DECREASED HUMIDITY (Fall and Winter):
- Cold air cannot hold much humidity; skin loses moisture
- Dry skin is less supple, more fragile, more easily irritated
- Pruritus is established, rash appears
- Commercial humidifiers can help (target greater than 50% humidity)
EXCESSIVE WASHING:
- Repeated washing removes water-binding lipids from stratum corneum
- Daily baths tolerated in summer but lead to excessive dryness in fall and winter
- Apply moisturizer WITHIN 3 MINUTES of bath to retain hydration
CONTACT WITH IRRITATING SUBSTANCES:
- Wool, household and industrial chemicals, cosmetics, soaps, detergents
- Cigarette smoke may provoke eczematous lesions on eyelids
- Atopic patients have lower threshold for irritant response
STAPHYLOCOCCUS AUREUS:
- Predominant skin microorganism in AD lesions
- Significantly increased even on non-affected skin
- Normally represents less than 5% of total skin microflora in persons without AD
- Antibiotics given systemically or topically may dramatically improve AD
AEROALLERGENS:
- House-dust mite is the most important aeroallergen
- Positive patch test rates: House dust 70%, mites 70%, cockroaches 63%, mold mix 50%, grass mix 43%
- Avoidance of aeroallergens rarely improves dermatitis significantly
FOOD:
- Consider food allergy in infants, young children, and selected older children with moderate to severe AD
- Most common offenders in children: Eggs, peanuts, milk, fish, soy, wheat (top 5 account for 90% of reactions)
- May cause urticaria, exacerbation of eczema, GI symptoms, or anaphylaxis
EMOTIONAL STRESS:
- Can trigger sudden widespread flare almost overnight
- AD is WORSENED by (not caused by) emotional stress
- Is an inherited genetic disease; explain this to patients who feel responsible for their disease
16. ASSOCIATED FEATURES OF AD
XEROSIS (DRY SKIN):
- Most common associated feature; itchy; worse in winter
- Dry skin → itching → eczema
- Avoid frequent washing; use mild soaps (Dove, Cetaphil); apply moisturizing creams or lotions
- Moisturizers most effective applied shortly after patting skin dry following bathing
ICHTHYOSIS VULGARIS:
- Disorder of keratinization; dry rectangular scales
- Dominant ichthyosis vulgaris is significantly associated with atopy
- White translucent scales on extensor aspects of arms and legs; improves with age
- Does NOT encroach on axillae and fossae
- Treatment: 12% ammonium lactate lotion/cream or urea cream (very effective)
KERATOSIS PILARIS:
- Very common; occurs more often and more extensively in AD patients
- Small (1-2 mm) rough follicular papules or pustules
- Posterolateral aspects of upper arms and anterior thighs most common; any area except palms and soles
- Peaks during adolescence; tends to improve thereafter
- May look like acne on the face (uniform small size differentiates from acne)
- Treatment: 12% ammonium lactate (Lac-Hydrin, AmLactin), urea cream (10-40%), salicylic acid 6% lotion
- Group V topical steroids for temporary redness reduction before important events
HYPERLINEAR PALMAR CREASES:
- Accentuated major skin creases of palms; more prominent with age and disease severity
- May be initiated by rubbing or scratching
- Moisturizers soften skin but do not improve the creases
PITYRIASIS ALBA:
- Hypopigmented, slightly elevated, fine scaling plaques with indistinct borders
- Affects face, lateral upper arms, thighs; common in children; usually disappears by early adulthood
- White round-to-oval areas 2-4 cm; become obvious in summer (areas do not tan)
- Loss of pigment is NOT permanent (unlike vitiligo)
- Treatment: No treatment needed unless eczematous; tacrolimus ointment 0.1% twice daily for a few weeks may be effective
OCULAR COMPLICATIONS:
- Cataracts: 1-25% prevalence; associated with chronic systemic steroid use
- Annual ophthalmologic screening recommended in chronic AD patients receiving systemic steroids
- Patients applying topical steroids to eyelids for more than 4 weeks should have intraocular pressure measured
17. TREATMENT OF ATOPIC DERMATITIS (Step-by-Step)
STEP 1: DRY SKIN CONTROL
- Daily bath: Apply moisturizer WITHIN 3 MINUTES of bath (before water evaporates) = "soak and smear"
- Pat skin dry gently before applying moisturizer to seal in moisture
- Use unscented petrolatum or cream (NOT lotion - less effective)
- Use mild soaps sparingly in axilla, groin, and feet only
- Humidify home in winter (target greater than 50% humidity)
- Avoid wool; use 100% cotton clothing
- Avoid fabric softeners, perfumes or makeup that burns or itches
- Maintain cool, stable temperatures; do not overdress
STEP 2: TOPICAL ANTI-INFLAMMATORY THERAPY
TOPICAL CORTICOSTEROIDS (TCS) - FIRST-LINE:
- Apply 2 weeks on, then rest 1 week, then restart
- Do NOT start with hydrocortisone or weak steroids - inflammation persists and patients lose confidence
- Use MID-TO-HIGH strength steroids initially for rapid control (within days)
- Apply ointment-based medications for dry skin
- Face and eyelids: Use Group V-VI (weak steroids like desonide) OR calcineurin inhibitors
- Lichenified plaques in adults: Group I-II + occlusion for 10-14 days
- Maintenance: Fluticasone ointment once daily on weekends to maintain improvements and delay relapse
PIMECROLIMUS (ELIDEL) 1% CREAM - Topical calcineurin inhibitor:
- Indicated: Short-term and intermittent long-term therapy for MILD TO MODERATE AD, age 2 and older
- Apply twice daily to affected skin
- Can be used on ALL skin surfaces including face, neck, intertriginous areas
- Stop when eczema clears or if no improvement after 6 weeks
- DO NOT use with occlusive dressings
- Absorbed at lower rate than tacrolimus; lower potential for systemic absorption
- Side effects: Burning and stinging (usually mild)
- FDA black-box warning: Avoid prolonged continuous use; avoid excessive UV exposure (tanning beds or UV treatment)
- "Prevention of flare" strategy: Early treatment at first signs of recurrence reduces flares requiring topical steroids
TACROLIMUS (PROTOPIC) OINTMENT - Topical calcineurin inhibitor:
- Indicated: Short-term and intermittent long-term therapy for MODERATE TO SEVERE AD
- 0.03% for children 2-15 years
- 0.1% for adults (and children in some countries)
- Apply twice daily; continue 1 week after clearing; do NOT use under occlusive dressings
- Efficacy similar to mid-potency steroid such as betamethasone valerate 0.12%
- SAFE on face and around eyes: Does NOT cause atrophy or pigmentary alterations; no increased IOP when applied to eyelids
- Systemic absorption is minimal even with large area treatment
- Side effects: Burning at application site (31-61% of patients); lasts 2 minutes to 3 hours; decreases after first few days
- FDA black-box warning: Avoid prolonged continuous use; avoid excessive UV/tanning bed exposure
- "Proactive strategy": Twice-weekly application prevents and delays AD exacerbations
CRISABOROLE (EUCRISA) 2% OINTMENT - PDE-4 inhibitor:
- Indicated: Mild to moderate AD in patients 2 years and older
- Apply twice daily to affected areas
- Improves severity scores and decreases pruritus
- Side effect: Pain at application site (most common)
- Co-administration with Group V or VI topical steroid can help with application site pain
STEP 3: TREAT INFECTION
BLEACH BATHS:
- Quarter to half a cup of household bleach (sodium hypochlorite) in full adult bathtub
- Effective as both antiinflammatory and antiinfective agent
- Can be done daily or as infrequently as weekly depending on disease severity
- Hypochlorous acid spray (Alevicyn) can be applied once to twice daily for pruritus and infected wounds
ANTIBIOTICS:
- Staphylococcus aureus colonizes eczematous lesions and worsens AD
- START oral antibiotics 2 DAYS BEFORE initiating topical steroid treatment
- Cephalexin (Keflex) or Cefadroxil (Duricef) are first choices
- Dicloxacillin is an alternative
- Oral antibiotics are more effective than topical antibiotics
INTRANASAL MUPIROCIN:
- Used in patients with recurrent infections to reduce nasal carriage of S. aureus
STEP 4: CONTROL ITCHING
ORAL ANTIHISTAMINES:
- Hydroxyzine: Sedating; most useful at bedtime to help patient sleep and suppress unconscious scratching
- Important note: Antihistamines have only MARGINAL therapeutic benefit for AD itself; they do NOT alter the course of the disease
- Nonsedating antihistamines have NO objective evidence of effectiveness for AD pruritus
TOPICAL ANTIHISTAMINES:
- Doxepin HCl cream 5% (Zonalon): Short-term (up to 8 days) management of pruritus in AD and LSC; apply 4 times daily with 3-hour intervals
- Drowsiness occurs in more than 20% (especially over large body surface areas)
- Side effects: Burning and stinging at application site
STEP 5: PHOTOTHERAPY
- Effective for mild, moderate, and severe AD
- Narrowband UVB 311 nm: Effective as monotherapy for moderate to severe AD; doses considerably lower than for psoriasis
- UVA1 (340-400 nm): Superior to conventional UVA-UVB for SEVERE AD
- Combined UVA-UVB: Also effective
- PUVA (psoralen + UVA): Effective but many clinicians avoid due to long-term carcinogenicity risk
- Low-dose UVA1 or narrowband UVB twice weekly for 4 weeks then once weekly for 4 more weeks appears to prevent relapse
STEP 6: SYSTEMIC IMMUNOSUPPRESSIVE AGENTS (Severe, Refractory AD)
Consider when patient has severe AD that has failed topical regimens and phototherapy.
CYCLOSPORINE A (CsA):
- Most commonly used systemic agent for severe refractory AD
- Inhibits T cells and cytokine gene expression
- Effective and well-tolerated in both children and adults
- Starting dose: 2.5 mg/kg/day (low dose preferred for safety); can go up to 5 mg/kg/day for severe disease
- Short-term preferred; long-term (up to 1 year) only in exceptional cases
- Disease may relapse despite treatment or recur soon after stopping
METHOTREXATE:
- Inhibits folic acid and impairs DNA synthesis
- Administered weekly (orally, subcutaneously, or intramuscularly): 7-25 mg weekly
- ALWAYS give folic acid supplementation (5 mg 24 hours after methotrexate, or 1 mg daily) to reduce side effects
AZATHIOPRINE:
- Purine analog; suppresses B cells and T cells
- Effective for severe AD
- Check THIOPURINE METHYLTRANSFERASE (TPMT) level BEFORE starting to determine safe dosing
MYCOPHENOLATE MOFETIL (MMF):
- Impairs purine synthesis; selectively affects B cells and T cells
- Highly effective for moderate to severe AD
- No serious adverse effects
- Administered orally 500 mg to 1 g twice daily
ORAL CORTICOSTEROIDS:
- Should NOT be routinely used for AD
- Use ONLY for severe unresponsive AD as a bridge therapy or when immediate relief is required
- High relapse rate after stopping; rebound flare possible
- Commercially available steroid dose packs (Medrol Dosepak) provide inadequate medicine - AVOID
- Risk of atopic cataracts with systemic steroid therapy
STEP 7: BIOLOGIC THERAPY
DUPILUMAB (DUPIXENT):
- Mechanism: Human monoclonal antibody (IgG4) that binds to IL-4 receptor alpha subunit (IL-4Rα) and inhibits BOTH IL-4 AND IL-13 signaling, including release of proinflammatory cytokines, chemokines, and IgE
- Indication: Moderate to severe AD in adults and adolescents whose disease is not adequately controlled with topical therapies
- Dosing: Initial 600 mg subcutaneous injection, then 300 mg every other week (adults and adolescents ≥18 years or 12-17 years weighing ≥60 kg); 400 mg initial then 200 mg every other week for 12-17 years weighing less than 60 kg
- Side effects: Conjunctivitis occurs in approximately 16% of patients; may lead to discontinuation; refer to ophthalmology if patient does not respond to topical over-the-counter measures
- AVOID live vaccines while on dupilumab
HOSPITALIZATION FOR SEVERELY RESISTANT CASES
- Short hospital stay rapidly controls condition that has had prolonged, unstable course
- Mean treatment time is 3.6 days
- Intensive topical treatments with wet dressings over topical corticosteroids in hospital setting
Home Hospitalization Protocol (weekend treatment):
- Designate family member as nurse; complete bed rest with bathroom privileges
- Cotton bedclothes; dust-free, animal-free room; temperature 68-70°F; humidity 70%
- Tepid tub bath with bath oil twice daily; emollient applied to moist body after bath
- Body lesions: Group II-V topical steroid cream or ointment twice daily ± vinyl suit occlusion 2-8 hours
- Face: Group V steroid cream or ointment twice daily
- Scalp: Daily shampoo + topical steroid lotion
- Systemic: Oral antibiotics (cephalexin or dicloxacillin) + sedating antihistamines (hydroxyzine 10-25 mg four times daily, or doxepin 10-25 mg four times daily)
18. FOOD ALLERGY IN ATOPIC DERMATITIS
Testing recommended for: Infants and young children with moderate to severe AD; selected older children with clinical history suggesting food allergy.
Common food allergens:
- Young children: Cow's milk, hen's eggs, peanuts, tree nuts, sesame seeds, wheat, soy
- Adults: Shellfish, fish, peanuts, tree nuts
- More than 90% of reactions in young children are caused by only 5 foods: Eggs, milk, peanuts, soy, and wheat
Testing approach:
- Skin prick test (SPT): Sensitivity 90%, specificity 50%; cannot diagnose FA alone
- IgE testing: High sensitivity but low specificity; many false positives
- Oral food challenge: Gold standard for confirming food allergy or tolerance
- Do NOT do broad food elimination based solely on positive IgE (low specificity; risk of nutritional deficiencies)
- 4 to 6 week targeted food elimination diet may be tried if specific allergen suspected
Natural history of common food allergies:
- Hen's egg: Resolves in 75% by age 7 years
- Cow's milk: Resolves in 76% by age 5 years
- Wheat: Resolves in 80% by age 5 years
- Soy: Resolves in 67% by age 2 years
- Peanuts: Persistent; only 20% resolve by age 5
- Tree nuts: Persistent; only 9% resolve after age 5
- Fish and shellfish: Usually persistent
- Sesame: Persistent; 20% resolve by age 7
PEANUT ALLERGY PREVENTION (current guidelines):
- Infants with severe eczema or egg allergy: Consider evaluation and introduce peanuts at 4-6 months after testing
- Infants with mild to moderate eczema: Introduce peanut-containing foods around 6 months
- Infants with no eczema or food allergy: Introduce peanuts at age-appropriate time per family preference
- Early introduction and regular consumption of peanuts DECREASES the development of peanut allergy
19. HIGH-YIELD CLINICAL PEARLS
- Topical steroid creams should NEVER be applied directly onto ulcers - it stops the healing process.
- Wet compresses in asteatotic eczema: Use for MAXIMUM 1-2 days only; prolonged use causes excessive drying.
- Medrol Dosepak (steroid dose packs) are INADEQUATE for poison ivy or severe AD - they cause rebound dermatitis.
- In hand eczema, ALWAYS consider patch testing even if the pattern looks like irritant dermatitis.
- Adult-onset recalcitrant eczema with no clear cause - rule out cutaneous T-cell lymphoma.
- Tacrolimus (Protopic) is SAFE on the face and around eyes; no skin atrophy unlike topical steroids.
- In stasis dermatitis, AVOID neomycin, parabens, lanolin - very high sensitization risk in venous skin.
- Generalized eczema or intractable pruritus in adults may be a sign of Hodgkin lymphoma.
- Bleach baths reduce Staphylococcus aureus colonization effectively in atopic dermatitis.
- Filaggrin mutation leads to weak skin barrier which leads to Staph colonization which leads to TH-2 dominant inflammation and worsened AD (the core cycle of disease).
- In poison ivy: Washing within 10 minutes removes ALL urushiol; after 30 minutes only 10% removed; after 60 minutes nothing can be removed.
- Pompholyx blister fluid does NOT spread the reaction (very common misconception among patients).
- Patch test must be read at 48 hours AND again at 3-7 days. Neomycin reactions may not appear until day 7.
- Before applying compression therapy for venous ulcers, ALWAYS check the Ankle-Brachial Index (ABI) first.
- Dupilumab (Dupixent) blocks IL-4 and IL-13 simultaneously; watch for conjunctivitis in about 16% of patients.
- Children do NOT simply outgrow atopic dermatitis - 58% of infants with AD still have inflammation 15-17 years later.
- Pompholyx cause: 67.5% allergic (cosmetics and hygiene products most common, then metals), 10% mycosis, 15% idiopathic atopic - test with patch testing and consider a low-metal diet if metal-sensitive.
- Stasis dermatitis: Brown skin discoloration is hemosiderin - iron remaining after RBCs leak out of veins due to increased hydrostatic pressure.
- Start oral antibiotics 2 days BEFORE initiating topical steroid treatment in AD with infection.
- Montelukast + fexofenadine combination is effective for prurigo nodularis; naltrexone also works but 41% relapse after stopping.
Notes from Habif's Clinical Dermatology - Chapters 3, 4, and 5. All treatments included; doses omitted as requested.