CH. 17 DISEASES OF THE SKIN SWCTA Dr. Michael J. Georges I. FUNCTIONS OF THE SKIN The skin or the integument is a vital organ A “protective wrap” Regulates body temperature Senses pain Keeps harmful substances & microorganisms from entering body Provides a shield from harmful effects of the sun Largest organ of the human body I. FUNCTIONS OF THE SKIN Indicates malfunction within the body through color changes Cyanosis (blue) is lack of O2-cardiovascular problem Jaundice (yellow) – indicates liver disease from accumulation of bilirubin in the blood Abnormal redness – due to polycythemia, carbon monoxide poisoning, & fever Pallor (whitening) may indicate anemia II. STRUCTURE OF THE SKIN Each layer of skin performs specific tasks OUTERMOST layer is the EPIDERMIS Consists of stratified or squamous epithelium Top layer of epidermis contains KERATIN – a tough, fibrous protein that protects skin from harmful substances Bottom layer of epidermis contains MELANIN – dark pigment in skin that protects body from harmful rays of the sun II. STRUCTURE OF THE SKIN DERMIS – “True Skin” SUBCUTANEOUS –lies lies below the epidermis Composed of connective tissue Supports blood & lymph vessels, elastic fibers, nerves, hair follicle, sweat glands & sebaceous (oil) glands under the dermis Connects the skin to underlying structures (i.e. muscle, fat) Contains adipose (fat cells) tissue – helps insulate body from cold & heat Fig. 18-1 pg. 397 Structure of the Skin III. CLASSIFICATIONS OF SKIN DISEASES Skin diseases are identified and classified according to characteristic lesions (size, shape, color & location) and other S & Sx’s Fig. 18-2 Skin signs pg. 398 PRURITIS – itching EDEMA – swelling ERYTHEMA – redness Inflammation –usually accompany lesions and are helpful in making a diagnosis (DX) III. CLASSIFICATIONS OF SKIN DISEASES VESICLES – small blister-like eruptions or larger fluid-filled lesions called bullae. PUSTULES – lesions that contain pus MACULAR – flat lesions PAPULAR – raised lesions ERYTHEMATOUS – reddened area due to inflammation &/or injury Nodules & tumors – hard to the touch Pruritis – itching, which accompanies many skin diseases, especially allergic & parasitic IV. INFECTIOUS SKIN DISEASES BACTERIAL IMPETIGO – is acute, contagious & common in children Caused by streptococcal & staphylococcal organisms in the nose & passed to the skin Erythema, reddened area develops and oozing vesicles and pustules form Area ruptures & yellow crust covers lesion Face & Hands most frequently affected Fever & enlarged lymph nodes may present Wash with soap & H20, dry, keep open to air IV. INFECTIOUS SKIN DISEASE BACTERIAL ERYSIPELAS – inflammatory skin infection caused by streptococci Commonly appears on face, arm or leg Infection begins where skin is broken Shiny, swollen, red rash initially develops, often with small blisters Red rash is hot & tender to touch Fever & chills present when infection severe Treatment with antibiotics (ABX) when severe IV. INFECTIOUS SKIN DISEASE BACTERIAL CELLULITIS - spreading infection of the skin most often caused by streptococcus Most common on the legs and begins with skin damage Affected area is swollen, red, & tender Sx’s may include fever & chills Treatment (TX)– prompt TX prevents the spread of infection to the blood & vital organs IV. INFECTIOUS SKIN DISEASES BACTERIAL FOLLICULITIS – inflammation of hair follicles by staphylococci Small number of pustules develop in follicle Commonly occurs in young men and affects thighs, buttocks, beard & scalp (Fig.18-4 p.400) TX-severe cases require oral ABX CARBUNCLES- clusters of boils. Arise in cluster of hair follicles Develop & heal more slowly than furuncles Mostly appears in men and commonly found on back of neck FURUNCLES – “boils” are large, tender, swollen raised lesions caused by staph (Fig. 18-5 p. 401) Appears in hair follicles on face, neck, breast, or buttocks The core of furuncle is necrotic & liquefies to form pus TX-moist heat, antiseptic skin cleansing, oral ABX, I & D VIRAL SKIN INFECTIONS Most common viruses cause cold sores or fever blisters & warts HERPES SIMPLEX – causes cold sores & fever blisters (Fig. 18-6 p. 401) VERUCCA VULGARIS – causes WARTS Keratinocytes proliferate making the surface rough Most common in children & young adults Affects mostly the hands (Fig. 18-7 p.402) Multiple & CONTAGIOUS – spread by scratching Reoccurs if virus remains in body, not serious May disappear spontaneously, not painful Should only be removed by an M.D. VIRAL SKIN INFECTIONS WARTS PLANTAR WARTS – found on the SOLES OF THE FOOT GROWS INWARD, unlike other warts on the body which grow outward (elevated) Painful, due to pressure on the soles of the foot when walking or standing Difficult to remove permanently GENITAL (VENEREAL) WARTS – very serious & difficult to remove (CH. 15) VIRAL SKIN INFECTIONS FUNGAL DERMATOPHYTES (FUNGI) – live on the dead, top layer of the skin Symptoms may or may not appear Serious infections – itching, swelling, blisters & severe scales Minor infections – mild irritation & swelling VIRAL SKIN INFECTION FUNGAL RINGWORM (TINEA) – caused by many different fungi. Classified by its location on the body (Table 18-1) Found on warm, moist areas of the body and hairy skin on head, groin, arms, & legs SX’s – mild scales, cracking skin, to painful raw rashes TX- keep area clean & dry, apply antifungal meds. TINEA CORPORIS – Body ringworm, smooth areas, arms, legs, body TINEA PEDIS – ”ATHLETES FOOT” soles, btwn toes, toenail TINEA CRURIS – “JOCK ITCH” groin & upper thighs TINEA CAPITIS – “SCALP” ringworm. HIGHLY CONTAGIOUS PARASITIC INFESTATIONS 3 Categories PEDICULOSIS – Louse (lice) infestations HEAD LICE – common among children Spread from head to head (direct) Indirect – combs, scarves, hats, bed linen,etc Itching – caused by saliva of lice penetrating skin & engorging on human blood Scratching – can open up skin to other invading organisms Adult head lice – hard to see, lay white eggs “NITS” along hair shaft TX – Medicated shampoo followed by fine tooth comb to remove nits PARASITIC INFESTATIONS PUBIC LICE – infest pubic hair and generally spread by sexual contact. Lice does not spread other STD’s TX – RX Cream BODY LICE – most common among underprivileged, transient people. Lice CAN SPREAD DISEASE – such as typhus epidemics among soldiers during war Prevention – good grooming & hygiene PARASITIC INFESTATIONS SCABIES “THE ITCH” – caused by a parasitic MITE HIGHLY CONTAGIOUS Female mite – burrows into skin folds of groin, under breasts, between fingers & toes. Lays eggs in tunnels of folds, eggs hatch, cycle begins again Spread via close contact & linked to other VD’s Blisters & pustules appear Itching – caused by hypersensitivity to mite & opens up skin to other bacterial infections Epidemics common in camps & barracks (poor living) TX & Recovery – Hot baths & scrubbing & meds. Underwear & bedding changed & washed frequently. V. HYPERSENSITIVITY OR IMMUNE DISEASES OF THE SKIN HYPERSENSITIVITY – ALLERGIC reactions of the skin. Emotional stress may trigger or exacerbate an allergy-caused skin disease. INSECT BITES – Bites & stings can produce local inflammatory reactions. Acute reactions – hives Chronic reactions – papules (solid elevations) Bullous - blisters HYPERSENSITIVITY OR IMMUNE DISEASES OF THE SKIN URTICARIA (HIVES) – VASCULAR REACTION OF THE SKIN TO AN ALLERGEN WHEALS – lesions round elevations with red edges & pale centers Extremely itchy Histamine released – cause blood vessels to dilate, followed by edema & intense itching Common causes – food, allergens & stress TX- steroids, antihistamines, topical creams HYPERSENSITIVITY OR IMMUNE DISEASES OF THE SKIN ECZEMA – AKA CONTACT DERMATITIS is a non contagious inflammatory skin disorder. Cause – sensitization that develops from skin contact with various agents, plants, chemical, & metals. Poison ivy and poison oak, dyes used for hair & clothes, metals, particularly nickel used in jewelry. S & Sx’s – Vesicles & bullae appear with itching. Scaly crusts form on ruptured lesions. Scratching – causes the lesions to burst & ooze which spreads the eczema. TX – Corticosteroids to reduce inflammation Fig. 18-10 p.406 HYPERSENSITIVITY OR IMMUNE DISEASES OF THE SKIN POISON IVY – causes extreme itching with blisters and hive-like swelling typical of a contact dermatitis Develops in few hours or few days Severity – depends on amount of plant resin on skin & sensitivity of ind. TX- Topical cortisone-type cream, gel or spray. Table 18-2 Common rashes caused by Drugs p. 407. DRUG ERUPTIONS – Adverse drug reactions manifest more often on the skin than any other organ system. Topical drugs – mild pimples over sm. Area to peeling of the skin Serious reactions may lead to anaphylaxis shock or death. Most common offending drugs are penicillin, sulfa, morphine, codeine, etc. VI. BENIGN TUMORS NEVUS (MOLE) – small, dark skin growth that develops from pigment-producing cells or melanocytes. Appear flat or raised & vary in size Most people have about 10 moles Usually harmless, but can become malignant Sudden changes in moles such as enlargement, irregular border, darkening, inflammation & bleeding are warning signs of malignancy (Fig. 18-15 & 18-16 p. 409) VII. SKIN CANCER BASAL CELL CARCINOMA – most common skin cancer. Slow growing, generally non-metastasizing (spreading) tumor. Develops on face of light skinned people exposed to sun Lesions begin as a pearly nodule with rolled edges that may bleed and form a crust Ulceration occurs and size increases if neglected TX- surgical removal, cauterize, or radiation. Fig. 18-17 to 18-19 p. 410. VII. SKIN CANCER SQUAMOUS CELL CARCINOMA – more serious than basal cell carcinoma because it grows more rapidly, infiltrates underlying tissue, and metastasizes in lymph system. Malignancy of the keratinocytes in the epidermis of people who are excessively exposed to sun. Lesion is crusted nodule that ulcerates & bleeds. May develop in any squamous epithelium of the body including the skin or mucous membranes lining a natural body opening (mouth, nose, ear, etc.) TX – complete surgical removal or radiation therapy. VII. SKIN CANCER KAPOSI’S SARCOMA – Purplish neoplasm of the lower extremities. Lesions – red to purple lesions varying from macules (flat) to nodules (hard nodes) This skin cancer is epidemic in AIDS patients Cause of 11% of AIDS-related deaths VII. SKIN CANCER MALIGNANT MELANOMA – the MOST SERIOUS skin cancer. Arises from the melanocytes of the epidermis. HIGHLY MALIGNANT and metastasis is early Sometimes develops as a mole that changes in size, color & becomes itchy & sore. TX-surgical removal with the surrounding lymph nodes to reduce metastasis Prognosis-depends on depth of infiltration, previous metastasis, & how completely the tumor is removed. Fig. 18-21 Malignant melanoma spread to brain. VIII. SEBACEOUS GLAND DISORDERS Hyperactivity of the sebaceous glands causes acne and chronic dandruff. Raised, horny lesions result from an excessive production of keratinocytes. ACNE (VULGARIS) – blackheads, pimples and pustules. Affects many adolescents, about 80% between the ages of 12 – 15. Mild form – non-inflammatory acne with few white & black heads. Inflammatory acne – severe breakout of pus-filled pimples & cysts that cause deep pitting & scarring SEBACEOUS GLAND DISORDERS ACNE Result of hormonal changes that occur at puberty Increased level of estrogen & testosterone stimulates not only growth at this time but also glandular activity SEBACEOUS GLANDS increase secretion of SEBUM, the oily fluid that is released through the hair follicles. If duct becomes clogged by dirt or make-up, the sebaceous secretion accumulates, causing a little bump or whitehead Sebaceous accumulation at the surface becomes oxidized and turns black, causing a blackhead Blackheads should not be squeezed or picked because the broken skin offers entry of bacteria that’s always present on the skin Once pyogenic (pus producing) bacteria enters the skin, pus forms and a pimple or pustule “whitehead” results. Squeezing the pimple spreads the infection TX- daily frequent & thorough washing to remove excess oil & bacteria. Dermatologist may prescribe topical or oral ABX. SEBACEOUS GLAND DISORDERS SEBORRHEIC DERMATITIS KNOWN AS “CHRONIC DANDRUFF” CAUSE-same as acne, an excessive secretion of sebum from the sebaceous gland SX’s- Oily scalp, with scales that form from excess sebum Can spread to face, ears & eyebrows TX – frequent shampooing with medicated shampoo and thorough brushing of hair loosens dandruff scales & washes out easily SEBACEOUS GLAND DISORDERS SEBACEOUS CYSTS- ACNE ROSACEA- formed when gland duct becomes blocked, sebum accumulates under the skin surface, forming a lump. These cysts are NOT considered serious, but they can rupture, allowing bacteria to enter. TX-incision & drainage or surgical removal condition that appears during or after middle age in persons with fair skin. Usually cheeks, chin & nose develop tiny pimples and broken blood vessels that eventually thicken and gives the nose a bulbous appearance. Cause: NOT KNOWN TX – Responds well to topical ABX IX. METABOLIC SKIN DISORDER PSORIASIS – a superficial recurring idiopathic (unknown cause) skin disorder characterized by an abnormal rate of epidermal cell production and turnover. Rapid replacement of epidermal cells results in formation of red, round, raised lesions with silvery scales. Occurs on elbows, knees, & scalp (mistaken for severe dandruff) which flairs up and has periods of remission & exacerbation Cause – NOT KNOWN TX-application of emollient cream, topical & oral steroids, coal tar cream & UV light. Severe psoriasis can be treated with anticancer meds. X. PIGMENT DISORDERS The main skin pigment, MELANIN, is interspersed among other cells in the epidermis. Skin color varies from light to dark depending on the number of melanocytes. Melanin production normally increases with exposure to the sunlight causing tanning. ALBINISM –A rare INHERITED disorder in which NO MELANIN is formed An Albino person has white hair, pale skin, & pink eyes Because melanin protects the skin, Albinos are prone to sunburn and skin cancer VITILIGO – A loss of melanin resulting in white patches of skin. White patches are well defined (demarcated) and may cover large parts of the body Hypo-pigmentation is most striking in dark-skinned people The affected skin is prone to sunburn NO CURE TX - SUNSCREEN XI. DIAGNOSTIC TESTS FOR SKIN DISEASES Skin conditions are normally identified by its characteristics such as size, shape, color, location & presence or absence of systemic S&SX’s Culturing the purulent lesion usually identifies the bacterial, fungal, and viral infections. Culture grows & specimen is identified under a microscope Biopsies (tissue sample) are usual for neoplastic (abnormal new growth) lesions, chronic eruptions, and nodular lesions Excised tissue is about 1/8 inch in diameter and is examined under a microscope. XII. SUMMARY The skin protects the body from various elements in the environment, it can become diseased in many ways. Skin infections may be caused by bacterial, viral, fungal & parasitic infestations. Skin diseases frequently manifest allergies due to hypersensitivity or immune conditions. Abnormal growth or neoplasms may be benign or malignant and range from the common mole to malignant melanoma (skin cancer). Skin lesions take many forms, each of which is significant in diagnosing the disease. The location of the lesion, whether it tends to recur, and whether it itches, are also factors in the diagnosis. To rule out systemic conditions, blood tests and other laboratory tests may be performed.