USMLE Step 3 (Fach) / Dermatology (Lektion)
In dieser Lektion befinden sich 7 Karteikarten
UWorld
Diese Lektion wurde von estoffel erstellt.
- Onychomycosis Risk factors:- Old age- Tinea pedis- Diabetes mellitus- Peripheral vascular disease Examination findings: Thick, brittle, discolored nails Diagnosis: KOH, periodic acid-Schiff stain, culture Treatment: - First-line: Terbinafine, itraconazole- Second-line: Griseofulvin, fluconazole, ciclopriox
- High-potency topical corticosteroids - Fluocinonide - Betamethasone diproprionate 0.05% → Used on thicker, extensor surfaces
- Keratosis pilaris Benign condition characterized by retained keratin plugs in the hair follicles. Clinical features:- Small, painless papules- Roughened skin texture- Mottled perifollicular erythema- Most common on the posterior surface of the upper arm- Can become pruritic in cold, dry weather- Associated with asthma and atopic dermatitis Treatment:- Topical keratolysis (e.g., salicylic acid, urea)- Emollients
- Treatment of acne vulgaris Comedonal acne:- Closed or open comedones on forehead, nose & chin- May progress to inflammatory pustules or nodules- Treatment: Topical retinoids, salicylic, azeleic, or glycolic acid Inflammatory acne:- Inflammed papules (< 5 mm) & pustules, erythema- Treatment:→ Mild: Topical retinoids + benzoyl peroxide→ Moderate: Add topical antibiotics (e.g., erythromyclin, clindamycin)→ Severe: Add oral antibiotics Nodular (cystic) acne:- Large nodules (> 5 mm) that can appear cystic- Nodules may merge to form sinus tracts with possible scarring- Treatment:→ Moderate: Topical retinoids + benzoyl peroxide + topical antibiotics→ Severe: Add oral antibiotics→ Unresponsive severe: oral isoretinoin
- Rosacea Epidemiology:- Sex: ♀ > ♂Age range: 30-60 years Trigger factors:- Hot weather, hot drinks, spicy food- Stress, alcohol, nicotine- Demodex mites Clinical features:1. Erythematotelangiectatic rosacea- Facial flushing- Persistent erythema of the face (together with telangiectasias)2. Papulopustular rosacea- Papules, pustules, and erythema3. Phymatous rosacea- Skin and sebaceous glands thicken- Inflammatory, widespread nodules- Rhinophyma: enlarged, bulbous nose (almost exclusively in males)- Similar changes may occur on the chin, forehead, cheeks, and ears4. Ocular rosacea - Conjunctival hyperemia (most common)- Blepharitis (inflammation of the eyelid margin), stye (hordeolum externum), chalazion- Dry eyes and foreign-body sensation- Keratitis- In contrast to acne, comedones are NOT present! Treatment:- Avoid trigger factors- For erythema, flushing, skin sensitivity, xerosis:→ Topical brimonidine→ Topical oxymetazoline- For papules and pustules:→ Topical agents for mild disease; Metronidazole (also for ocular rosacea), Azelaic acid, Ivermectin, Sodium sulfacetamide→ Oral agents for moderate to severe disease and refractory disease: Tetracyclines: e.g., doxycycline (also for ocular rosacea), tetracycline, minocycline, Isotretinoin (first-line for phymatous rosacea)- Laser therapy: for erythema, telangiectasias, and phymatous rosacea - Surgical therapy: for phymatous rosacea; includes electrocautery and dermabrasion
- Decubitus ulcers An area of unrelieved pressure resulting in ischemia, cell death, and necrotic injury of epidermisand soft tissue Etiology:- Bed confinement- Reduced perception of pain- Skin breakdown (maceration) due to urinary or stool retention Predisposing factors: diabetes mellitus, reduced skin perfusion (from peripheral artery disease, heart failure, vasoconstriction), polyneuropathy, cachexia, old age, multimorbidity, malnourishment Primarily localized over bony prominences: sacrum, heel, greater trochanter, lateral malleolus, elbows Therapy/prevention:- Conservative management→ Pressure relief of the affected or vulnerable area with position changes (every 2 hours) and an alternating pressure mattress→ Skin care: keeping skin moist, preventing breakdown, as well as keeping it clean of urine and stool → Wound treatment (e.g., removal of necrosis, hydrocolloid dressing)→ Secondary prophylaxis: mobilization, optimized diet, control of infection- Surgical management for severe cases: Debridement, eventually plastic reconstruction
- Common skin infections Erysipelas- Streptococcus pyogenes- Superficial dermis & lymphatics- Raised with sharply demarcated borders- Rapid onset & spread- Fever, chills common Cellulitis- Streptococcus pyogenes, MSSA- Deep dermis & subcutaneous fat- Ill-defined with flat borders- Indolent course (over days)± Fevers later in course Abscess- MSSA, MRSA- Dermis or subcutaneous space- Fluctuant, tender nodule- Purulent drainage± Fever & surrounding cellulitis