Structure of the Skin

1. Structure of the Skin • The largest organ of the body. Its surface area is responsible for the regulation of body temperature • Has three layers • Epidermis which contains keratinocytes. Keratinocytes contain keratin which is a strong tensile protein responsible for much of the skin’s physical barrier properties. • Has five inner layers of the stratum corneum at the top and the stratum basale • The stratum basale is primarily made up of stem cells keratinoblasts, melanin producing melanocytes and merkel cells for touch perception and langerhans cells of the immune system • Dermis is the layer of the skin that contains blood vessels, immune cells and fibroblasts that produce collagen and elastin. Mast cells in this layer release histamine which produces hives in response to allergic reaction • Hypodermis contains a fatty layer where adipocytes are located. This is attached to the fascia of muscles

2. Picture courtesy of : http://www.best-anti-aging-guide.com/images/human-skin.jpg

3. Functions of the skin • Provides a physical barrier to infections • Provides a barrier to the lose of water • Temperature regulation via sweating • Enable the sense of touch • Vitamin D is synthesized from cholesterol

4. Medical terminology involving the skin • Macule: flat pigmented lesion • Papule: Slightly raised lesion (<5 mm) (pimple) • Maculopapular: combination of the two usually the papule is in the center of the macule. Sometimes called morbilliform (“measle like”) • Erythema: beffy red section of skin • Plaque: raised area of skin with clear borders. • Nodule : a raised lesion (> 5mm) • Vesicle: a small raised lesion filled with clear fluid(Blister) • Bulla: a large raised lesion filled with clear fluid • Pustule: a raised lesion filled with pus and bacterially infected fluids

5. Diseases of the skin • Autoimmune diseases of the skin • Psoriasis. In psoriasis the immune system of the body attacks the cells of the upper layers of the skin. The patient develops rashes, intense erythema that leads to scales and blisters localized to plaques areas. Can be painful • T cells enter the epidermis and attack the keratinocytes of the skin which produce chronic inflammation

6. Drugs used for Psoriasis

7. ATOPIC DERMATTIS (ECZEMA) • Eczema is similar to psoriasis but less severe • Eczema is believed to be a hereditary allergic reaction of the skin to a normally benign antigen(s) • Eczema is sometimes called “atopic dermatitis” and is commonly associated with asthmatic patients • Affected areas are itchy, red, and warm to the touch. Lesions may enlarge and become scaly. The rash are very itchy and the scratching can damage the skin further. • Treatment includes: • Topical Steroids • Vitamin D derivatives (Dovonex) • Vitamin A derivatives (retinoids): Differin® (Adapalene) • Topical immune modulators: Pimecrolimus (Elidel®)

8. Acne Vulgaris • Inflammatory reaction in the skin called by excessive production of sebum in the sebaceous glands of the skin located near hair follicles. • Bacteria known as Propriobacterium acnes feeds on the fats and release fatty acids which causes the skin to become inflammed • A severe form of acne is nodulocystic acne which can form life long scars • Therapy: • Nodulocyticacne: Accutane ® (isotretinoin) A oral medication. • Must be registered in the FDA’s iPLEDGE system

9. Drugs used for Acne Vulgaris

10. Bacterial Infections • Most commonly seen infections are impetigo in children and folliculitis in adults • Both are caused by staphylococcal infections • Cured by penicillin type antibiotics: • Dicloxacillin 500 mg capule three times a day for 10 days

11. Topical Antifungal Agents

12. Cancers of the skin • Any skin lesion that is large, raised, asymmetric, changes in color, and has raggy edges should raise the suspicion of cancer • Malignant melanoma is a cancer of the pigment producing cells of the skin and can be fatal if allowed to spread to other areas of the body • Basal Cell Carcinoma is a serious cancer; however, it can be cured with chemotherapy

13. Drugs for skin cancer • Actinic Keratosis: a small nodule on skin due to sun exposure (may be precancerous)

14. Skin manifestations to drug allergy • Skin is often the window to seeing an incipient drug allergy • Intense itching, wheals, hives may indicate an Type 1 hypersensitivity to a drug (anaphylactic reaction) • Penicillins and other beta lactams • Sulfa drug • Antiseizure drugs (Carbamazepine) • Upon subsequent exposure a life threatening reaction can occur • Morbilliform reaction: Type 4 hypersensitivity to a drug. Usually occurs with 72 hours after drug exposure • Usually not life threatening but uncomfortable to the patient

15. Stevens Johnson Syndrome and Toxic Epidermal Necrolysis • SJS and TEN represent a dermatological emergency • The reaction involves confluent separation of the epidermis from the dermis and a denuding of the skin • Therapy involves that used for severe third degree burns • Common drug precipants: Penicillins, Sulfasalazine, phenytoin, lamotrigine, Levetiractam , allopurinol, phenobarbital, ibuprofen http://www.youtube.com/watch?v=BC-OLAoqCk4

16. Topical Corticosteroids • Used for various autoimmune (acne, dermatitis) and allergic reactions of the skin