Skin Diseases & Disorders

Skin Diseases & Disorders Introduction to Human Diseases Chapter 16

Skin Anatomy • Stratum corneum • Stratum germinativum • Keratin • Melanin • Sebaceous glands • Sudoriferous glands • Hair follicles

Skin Lesions Flat: macules Elevated: Solid: papules, nodules, wheals, tumors Liquid-filled: vesicles, bullae, pustules, cysts

Psoriasis • Chronic, noninfectious inflammatory disease of unknown etiology • Affects millions, females more than males • Dominant trait (variable penetrance) • Usually begins in childhood • Environmental influences may affect presentation

Psoriasis • Characteristic silvery scales on lesion • Usually elbows, knees, scalp, gluteal cleft, finger and toenails • Treatment: UV light, anthralin past or tar with UV, methotrexate

Urticaria (Hives) • Also called wheals • Episodic inflammatory, allergic reaction in a localized area of skin • Majority of cases are acute, not chronic • Migratory lesions • Itchy, raised, erythematous, warm lesions that blanch when pressed

Urticaria • Localized capillary dilation & fluid transudation • Histamine is most important chemical mediator • Up to 20% population has had at least one episode in lifetime • Treatment: antihistamines, epinephrine, steroids, avoidance of allergens

Acne Vulgaris • Inflammatory disease of sebaceous glands and hair follicles • Characterized by comedos, papules, pustules • Typically appears during puberty • More severe forms in males • More persistent in females • May involve scarring

Acne Vulgaris • Sebaceous gland plugged by cornified cells • Sebaceous secretions continue, increasing size of lesion • Treatment: Vit A, benzoyl peroxide, tetracycline, erythromycin, estrogen, Accutane (related to Vit A), drying or pealing agents, topical antibiotics

Alopecia • Absence or loss of hair, most notable on the head • Etiologies: numerous • Systemic diseases or treatments • Types • Scarring: fibrosis & loss of follicles • Non-scarring: no follicle loss, reversible

Alopecia Types: Generalized Localized Male pattern baldness frontotemporal loss, then midfrontal recession and near vertex Female pattern baldness central scalp

Alopecia • Treatment • Minoxidil • Treatment of androgen levels • Autografting, etc

Furuncles • Furuncle: • Boil • Infection of a hair follicle • Self-limited usually • Increases during and after puberty • Usually staphylococcal infection

Carbuncles • Several or a group of infected follicles • Infection deeper in dermis and subcutaneous tissues • Broad, erythematous, slowing evolving mass • Drains through multiple openings • Common sites: back of neck, back of trunk, & lateral thighs

Pediculosis • Lice infestation = insect infestation • Most commonly on body, scalp, and pubic area (pediculosis corporis, capitis, pubis or crabs) • Lice feed on blood, lay eggs (nits) in hair or clothing, hatch in 2-3 weeks • Acquired via close contact with infected people

Pediculosis • Dx: visualizing lice or nits • S/S: itching, excoriations, • Rx: Lindane or pyrethrin lotions & shampoo, laundering clothes, bedding, etc.

Decubitus Ulcers • Necrotic skin & subcutaneous tissues • Most commonly in ischemic sites • Lack of blood supply often due to prolonged periods of immobility and pressure on that body part • Also called pressure sores • Most common in incapacitated, immobilized, paralyzed patients

Decubitus Ulcers • Sequence of skin changes • Bony prominence & increased pressure • Shiny, erythematous skin • Shallow ulcer forms, becomes deeper • Forms blisters, necrosis, drainage • Treatment: relieve pressure, topical antibiotics, surgical debridement, etc.

Corns & Calluses • Corns: • Hardened thickenings of stratum corneum • Central keratinous core • Calluses: • Localized hyperplasia of same layer • Has a definite border • Most common on feet & other areas of repeated trauma • Especially 5th toe

Corns & Calluses • Result from repeated trauma due to pressure, friction • Orthopedic deformities, abnormal weight-bearing • More common in diabetics, peripheral vascular disease • Treatment: • Keratolytic ointments, orthopedic devices, debridement, local steroid injections, metatarsal & corn pads

Dermatophytoses • Chronic superficial fungal infection • Usually categorized by region it infects • Tinea capitis (scalp), children mostly • Corporis (ringworm) • Unguim (toes), pedis (athlete’s foot) • Cruris (groin, “jock itch”) • Fungi infect dead cells (keratin) • Only in stratum corneum, hair, nails

Dermatophytoses • Diagnosis: via KOH prep • Treatment: various skin and scalp infections treated by topical fungicides • Nail infections treated by weeks-several months of oral fungicides

Scabies • Infection by skin mites • Caused by contact with scabies-infested patients • S/S: nocturnal itchiness • Small, discrete lesions • Usually in finger webs, sides of hands & feet, waist, ankles, extensors of elbow and knee

Scabies • Dx: visualization of mites on scrapings under microscope • Rx: permethrin, lindane, crotamiton topically

Impetigo • Contagious, superficial skin infection • Often self-limiting but may last for weeks if untreated • Usual cause is staph or strep bacteria • Common in children in close contact • Treatment: antibiotics

Impetigo • Two types • Bullous type • staphylococcus a. • Vesicular type • Streptococcal • Honey-colored crusting lesions

Warts • Also called verrucae • Benign skin lesions that are epidermal hypertrophy • Infection by papilloma viruses • Various viruses affect different parts of the body • Caused by direct contact or autoinnoculation

Warts • Most common in children & young adults • Types • Common, filiform, flat, genital, plantar, periungual • Treatment: • Keratolytics, liquid N2, laser, salicyte acid plasters, etc.

Scleroderma • Multisystem disease of unknown etiology that causes progressive fibrosis of the skin and internal organs • 2 forms: • 1. Skin only • 2. Skin & visceral involvement • Autoimmune etiology suspected • Females predominantly • Age 30-50 YOA

Scleroderma • Almost all have Raynaud’s phenomenon • Vasoconstriction, white to blue to red • Four syndromes: • Acrosclerosis (skin hardening first in hands then face) • CREST syndrome (includes skin, finger & esophageal involvement) • Diffuse systemic sclerosis (most severe) • Morphea (localized linear skin changes)

Scleroderma • Treatment • Chemotherapy with immunosuppressives • Steroids, colchicine • Antihypertensive & vasodilator drugs • Plaquenil, hydroxychloroquine

Dermatitis • A range of inflammatory diseases of the skin • Typically have erythema, pruritis, and a variety of skin lesions • May be acute, subacute, or chronic • Some types • Seborrheic, contact, atopic

Seborrheic Dermatitis • Chronic sebaceous gland disease • Increase in amount of secretions and change in quality of secretions • In infancy: • cradle cap • resolves by 8-12 months without treatment

Seborrheic Dermatitis • Often occurs with nervous system disease or other disease • Treatment: shampoos (selenium, zinc), topical steroids • Skin lesions • Moist, dry, or greasy • Brown-yellow or red • Scalp, eyelids, beard, chest, axillae, groin, trunk • dandruff

Contact Dermatitis • Caused by direct contact of irritative substance or contact with substance to which patient is allergic or sensitive • Drugs, plants, additives, latex, wool, etc. • S/S: erythema, warmth, edema, vesicles • Dx: via patch test, allergy testing • Rx: usually self-limiting, avoidance

Latex Allergy • Range of hypersensitivity reactions to latex, a product derived from rubber • May be contact dermatitis, urticaria, GI symptoms, facial symptoms, anaphylactic shock • Higher risk: frequent contact with latex products, asthma hx, banana, avocado, or topical fruit allergy

Latex Allergy • Dx: serum test for IgE for latex and via clinical signs • Treatment: avoidance, epinephrine if needed

Atopic Dermatitis • Skin inflammation of unpredictable course • Highest incidence in children • 3-5% population by 5 YOA • 70% have family history of asthma, allergic rhinitis, atopic dermatitis

Eczema • More generic term than used in this textbook • Most common inflammatory skin disease • May be acute, subacute, chronic • Components: • Erythema, scales, vesicles

Herpes-related skin lesions • Etiology is HSV-1 • Characteristic lesion are clusters of vesicles • Cold sores/fever blisters: perioral • Herpes zoster (shingles): dermatomal distribution anywhere on body

HSV-related skin lesions • Paresthesias (tingling, burning, etc) or pain along dermatome precede vesicular rash eruption • Treatment: acyclovir and other antiviral medicines

Basal Cell Carcinoma • Originate in basal cell layer of epidermis • Locally invasive • Slow growing • Metastases are rare • Most common in fair-skinned males over 40 YOA

Squamous Cell Carcinoma • Originate in epidermis • Produce keratin • Greater risk of metastasis • More common in fair-skinned males over 60 YOA • Sun exposure is a risk factor

Malignant Melanoma • Abnormal growth of melanocytes in the epidermis and dermis • Most common type is superficial spreading type • Increasing incidence • Greater risk in fair-skinned, excessive sun exposure in first 10-18 years of life

Malignant Melanoma • Metastases common • Treatment: surgical excision, regional lymph node excision, chemotherapy, and/or radiation • Poorer prognosis if vertical growth rather than horizontal growth predominates in primary lesion

Skin Diseases & Disorders