practical approach to dermatology richard p. usatine, m.d. director of medical student education...
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Practical Approach to Dermatology
Richard P. Usatine, M.D.Director of Medical Student EducationUTHSCSA 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 MRIMRI
Take home points
• Learn the patterns
• Look at nails, hair, mucus membranes, hands, feet for clues to diagnosis
• Use understanding of patterns