Dermatology

Chondrodermatitis Nodularis Helicis

Tenderness and ulceration of ear helix or antihelix due to chronic pressure on the ear Elderly Treatment → Pressure avoidance

Erythema Nodosum

Panniculitis → Inflammation of subcutaneous adipose tissue → Delayed hypersensitivity Etiology Infection Strep Coccidioides Yersinia TB Drug Sulfa drugs Antibiotic OCP Inflammatory IBD Crohn Ulcerative Colitis Sarcoidosis Behcet syndrome (Erythema nodosum-like lesions) Presentation Anterior shin nodules Painful Erythematous Spread → Turn brown/gray Fever Joint pain False ⨁ VDRL Diagnosis...

Alopecia

Hypopigmentation

Tinea Versicolor Fungus → Malassezia furfur Scaly macules Varying color Areas don’t tan Diagnosis KOH prep → Spaghetti and meatballs Treatment Selenium shampoo Ketoconazole Vitiligo Autoimmune destruction of melanocytes Sharply demarcated patches White Complete depigmentation Diagnosis Woods lamp Biopsy → No melanocytes Treatment Local High potency topical steroid Tacrolimus...

Hyperpigmentation

Mole Benign From melanocytes If hair inside definitely benign If ABCDE biopsy Asymmetry Border irregular Color mixed Diameter >5mm Evolving Dermatofibroma (Benign fibrous histiocytoma) Nontender hyper pigmented nodule <1cm Young patient Lower extremity Pinching ⇒ Central dimple Benign Cosmetic excision Seborrheic Keratoses Benign From keratinocytes GI cancer → Explosive onset of...

Shingles

Etiology Varicella zoster virus Dormant in dorsal root ganglion sensory neurons Age >60 → Immune compromised Presentation Rash Painful prodrome Vesicular → Similar to chicken pox rashes Dermatomal distribution Never cross midline Diagnosis Clinical Complication Postherpetic Neuralgia After shingles in 15% Presentation Pain over the area Treatment TCA Amitriptyline...

Blistering Disease

Pemphigus Vulgaris Etiology Autoimmune → Antibodies split the dermis → Desmosome Drugs ACE inhibitors Penicillamine Phenobarbital Penicillin Presentation 30-50y Bullae that easily rupture (thin walled) Mouth involved Fluid loss Infection Life-threatening Nikolsky sign → Skin debudes by mild pressure Diagnosis Clinical Most accurate → Biopsy → Ab on immunofluorescence Treatment Systemic prednisone Wean...

Papulosquamous Disease

Seborrheic Dermatitis Etiology Autoimmune against fungus (Maelezzi sp.) Skin hypersensitivity to dermatophytes AIDS Parkinson Also caused by Cradle cap in infants Presentation Rash, scales, flakes Wherever there is hair No hair, no rash Treatment Selenium Shampoo Zinc pyrithione Shampoo Topical steroids Hydrocortisone Alclomethasone Antifungals Ketoconazole Psoriasis Presentation Silvery scaly...

Eczematous Rashes

Atopic Dermatitis (Eczema) Etiology Mast cell overactivity Mixture of type 1 and 4 hypersensitivity Presentation History of Asthma Allergic rhinitis Family history of atopy Onset <5y Pruritus Scratching → Scaly rough skin (Lichenification) Eosinophilia ↑IgE Complications Staph infection → Impetigo Cephalexin Mupirocin Retapamulin HSV infection → Eczema Herpeticum IV acyclovir → Treat infants...

Skin Malignancies

Malignant Melanoma Etiology Sun exposure Presentation A → Asymmetry B → Border irregular C → Color irregular D → Diameter >5-6 mm E → Evolution over time → Worst prognostic Ugly Duckling sign → One lesion different from others Black lesion WITHOUT hair Pruritus in a changing skin lesion Diagnosis Excisional Biopsy Punch Biopsy if big...

Hypersensitivity

Urticaria Type 1 hypersensitivity IgE-Mast cells Histamine Annular red papule Blanch with force If anaphylaxis → first Epinephrin IM If no anaphylaxis Steroid H1, H2 blockers Erythema Multiform Triggers Recurrent HSV Mycoplasma Coccidioidomycosis Can be a drug reaction Presentation Target lesions EM Minor → NO mucus membrane involvement EM Major Can involve mucus...

Skin Infections

Impetigo Etiology Superficial infection Staph = Strep Presentation Weeping Crusting Oozing Draining Complications Bullous Impetigo → Staph → Can progress to SSSS Scarlet fever → Strep → Sand-paper rash Treatment Amoxicillin Clindamycine Mild → Topical Mupirocin Ratapamulin Bacitracin Severe (Fever) → Oral Dicloxacillin Cephalexin Community acquired MRSA Doxycycline Clindamycin TMP/SMX...