Practical Approach to Dermatology Richard P. Usatine, M.D. Director of Medical Student Education UTHSCSA Department of Family and Community Medicine

Goals of lecture: Demonstrate a practical approach to the diagnosis of skin conditions using pattern recognition review dermatology patterns by: –viewing multiple images –distinguishing between common and uncommon patterns –observing local and regional morphology

Primary Lesions Macule papule plaque nodule wheal (hive) pustule vesicle bulla

TINEA VERSICOLOR

DERMATOFIBROMA

Secondary (Sequential) Lesions scale crusts erosion ulcer fissure atrophy excoriation lichenification

Strategies for Diagnosis Use magnification Feel lightly Palpate deeply Distribution Local patterns - groups, rings, lines

Looking for clues beyond the rash Look at nails, hair, mucus membranes, hands, feet –nail pitting for psoriasis –scalp may be clue to seborrhea elsewhere –lichen planus may show a white lacy pattern in the mouth –fungal infection on the feet with ID reaction on the hand

Think Pathophysiology Infections Inflammatory Processes - dermatitis, seborrhea Acne and related disorders Immunologic Benign and premalignant growths Malignancies

Infections bacterial viral fungal infestations

Bacterial infections of skin Impetigo, cellulitis, abscess Folliculitis Furuncle, carbuncle, abscess Necrotizing fasciitis Erythrasma, pitted keratolysis

Impetigo superficial skin infection of the epidermis characterized by translucent (“honey”) crusts caused by S. aureus and strep. pyogenes (GABHS) Cephalexin and Dicloxacillin Bactroban topical

Ecthyma and Bullous Impetigo Two variations of impetigo Ecthyma has a ulcerated “punched-out” base Bullous impetigo is more often caused by S. aureus

Erysipelas specific type of superficial cellulitis prominent lymphatic involvement. GABHS; H. flu in children face or leg admit if toxic or extensive involvement otherwise, oral Augmentin with close follow-up

Flesh-Eating Bacteria Necrotizing Fasciitis - Type 1 –Mixed anaerobes –Gram negative aerobic bacilli –Enterococci Type 2 –Group A strep Bisno, Stevens. Streptococcal Infections, NEJM, Jan 1996

Diagnosis of Necrotizing Fasciitis diffuse swelling of arm or leg follow by bullae with clear fluid which become violaceous in color marked systemic symptoms can lead to cutaneous gangrene, myonecrosis, and shock

Cellulitis vs. Necrotizing Fasciitis necrotizing fasciitis may look like cellulitis at first cellulitis only requires antibiotics necrotizing fasciitis requires surgical debridement along with antibiotics

Viral HPV Herpes Varicella/Zoster

Burrow

Infestations scabies - Elimite lice - Nix Permethrin

Fungal Infections Tinea pedis Tinea capitis Tinea corporis Tinea cruris Onychomycosis Tinea versicolor

Granuloma annulare

Common Types of Dermatitis (Inflammation) Hand Eczema Atopic Dermatitis Contact Dermatitis Seborrheic Dermatitis

Cutaneous Anthrax MRI

Take home points Learn the patterns Look at nails, hair, mucus membranes, hands, feet for clues to diagnosis Use understanding of patterns