Chapter 27 Skin Disorders

Pemphigus

Autoimmune disorder Autoantibodies disrupts cohesion between epidermal cells: causes blisters (bullae) to form; skin sheds, leaving area painful and open to secondary infection; may be life threatening if extensive e.g., Steven-Johnson syndrome Systemic glucocorticoids and immuneosuppressants

Bacterial Infections

Cellulitis: infection of the dermis and subcutaneous tissue; usually secondary to an injury; may be iatrogenic; causative organism: usually staphylococcus aureus, sometimes Streptococcus Frequently in lower trunk and legs: area becomes red, swollen and painfil; red streaks may develop running along lymph node network Furuncles: begin at hair follicles, face, neck, back; frequently drains large amounts of purulent exudate; autoinoculation: squeezing boils can result in spread of infection to other areas of the skin Carbuncles: collection of boils that coalesce to form a large infected mass

ABCD of Melanoma

Change in: -Appearance -Boarder -Color -diameter

Layers of Skin

Epidermis- avascular Dermis Subcutaneous Tissue (hypodermis)

Contact Dermatitis

Exposure to an allergen: metal, cosmetics, soaps, chemcicals, plants -Sensitization: occurs at first exposure (wont have reaction first time) -Pruritic rash develops at site a few hours after exposure Direct chemical or mechanical irritation: doesn't involve immune response, inflammatory due to direct exposure -removal of irritant -reduction of inflammation with topical glucocorticoids

Function of Skin

First line of defense Prevents excessive fluid loss Control of body temperature Sensory Perception Synthesis of Vitamin D

Squamous Cell Carcinoma

Painless, Malignant tumor of the epidermis Lesions most commonly found on exposed areas of skin or oral cavity: face, neck, base of tongue Excellent prognosis when lesion is removed with reasonable time Invasive types arise from premalignant conditions

Skin Lesion

Physical appearance of lesion necessary to make diagnosis Skin lesions may be caused by -systemic disorders -liver disease -systemic infections -chickenpox -Allergies to ingested food/drugs -localized factors

General Treatment Measures

Pruritus: topical agent to reduce sensation; may be treated by antihistamines or glucocorticoids Avoidance of allergens: reduces risk of reoccurrence Infection: may require antibiotic treatment Precancerous Lesions: surgery, laser therapy, electro-dessication

Urticaria

Results of type 1 hypersensitivity: ingestion of substances Lesions are highly pruritic Often part of anaphylaxis (cant breath): check for swelling around mouth and check airway; administer EpiPen or other first aid as required

Pruritus

Associated with: allergic responses, chemical irritation from insect bites, parasite infestation Mechanisms not fully understood: histamine release is known Infection may result from breaking the skin barrier due to itching or scratching

Skin Infections

Bacterial Infections: cellulitis, Furuncles Impetigo Acute Necrotizing Fasciitis

Hypodermis (subcutaneous)

Beneath Dermis: connective tissue, fat cells, macrophages, fibroblasts, larger blood vessels, nerves

Keratoses

Benign lesion usually associated with aging of skin damage Seborrheic keratoses: proliferation of basal cells; leads to waxy, oval elevated spot Actinic Keratoses: in skin exposed to ultraviolet radiation; common with fair skin, lesions appear to be pigmented, scaly patches; can develop into squamous cell carcinoma

Psoriasis

Chronic Inflammation skin disorder Onset usually in the teen years Psoriasis results from abnormal T Cell activation: excessive proliferation of keratinocytes; cellular proliferation is generally increased Lesions found on face, scalp, elbow, knees: itching or burning sensations Treatment: glucocorticoids; tar preparations, anti-metabolites

Atopic Dermatitis

Common in infancy: rash is erythematous with serous exudate; occurs on face, chest, shoulders In adults, rash is dry, scaly, and pruritic; often with flexor surfaces Chronic inflammation results from response to allergens: eosinophilia and increased serum IgE levels Potential Complications: secondary infection Treatment: topical glucocorticoids, antihistamines

Impetigo

Common infection in infants and children Common on face Pruritus commone: leading to scratching and further spread of infection Topical antibiotics in early stages Systemic administration is lesions are extensive

Dermis

Connective Tissue: containing elastic and collagen fibers Flexibility and strength of skin Contains nerves and blood vessels -includes sensory receptors for pressure, touch, pain, heat/cold Sympathetic Nervous System: controls blood flow to this layer of skin; fight/flight response; pallor

Inflammatory Disorders

Contact Dermatitis: a rash Urticaria: hives Atopic Dermatitis: eczema Psoriasis Pemphigus Scleroderma

Diagnostic Test for Skin Lesions

Culture and staining of specimen: for bacterial infections Biopsy: detection of malignant changes; safeguard prior to or following removal of skin lesions Blood Tests: helpful in diagnosis of conditions due to allergy or abnormal immune reaction Skin testing: using patch or scratch method

Verrucae

HPV types 1-4: frequent in young kids and adults Plantar warts are common Spreads by viral shedding of skin May resolve spontaneously with time Genital Warts: types 6 and 11

Appendages of Skin

Hair Follicles: stratum basle-hair producing; arrector pili muscle associated with hair follicle Sebaceous glands: produce sebum; secretion increases at puberty, influence of sex hormons Sweat Gland: eccrine (all over body); Apocrine (axillae, scalp, face, external genitalia

Viral Infection

Herpes Simplex Verrucae: warts

Malignant Melanoma

Highly mastastatic form of skin cancer Develops in melanocytes in stratumbasale (from mole) Often appear with multicolored lesions with irregular boarder; grows quickly, change in color, size texture, may bleed Surgical removal and radiation plus chemotherapy

Epidermis

Karatin; water proofing of skin Melanin: skin pigment; determines skin color Albanism: lack of melanin production Vitiligo: small areas of hypo-pigmentation Malsama: patches of darker skin

Skin Tumors

Keratoses Squamous Cell Carcinoma Malignant Melanoma Kaposi's Sarcoma

Types of Lesions

Location Length of time lesion has been present Changes occurring over time Physical appearance: color, elevation, texture, type of exudate Presence of pain or pruritus

Common Skin Lesions

Macule: flat, diff color than skin Nodule: firm, rised, deep, ranges in size Papule: small, solid elevation Pustule: raised with a "head" filled with exudate Vesicle/blister: thin wall, raised, filled with serous exudate Plaque: slightly elevated, flat, scale-like Ulcer: cavity in tissue Fissure: crack in tissue

Scleroderma

May occur as skin disorder May be systemic and affect viscera Primary cause is unknown: increased collagen disposition is observed in all cases; inflammation and fibrosis with decreased capillary networks- hard, shinny, tight, immovable areas of skin; impaired movement of mouth and eyes May cause renal failure, intestinal obstruction, respiratory failure, due to distortion of tissue

Acute Necrotizing Fasciitis

Mixture of aerobic and anaerobic bacteria are usually at site Severe inflammation and tissue necrosis: bacteria secretes toxins that break down fascia and connective tissue, causing massive tissue destruction Often history of minor trauma or infection in the skin and subcutaneous Systemic toxicity developers with fever, tachycardia, hypotension, mental confusion, disorientation, possible organ failure Treatment: aggressive antimicrobial thearapy, fluid replacement

Fungal Infections (Mycoses)

Most are superficial -Candida: ass. with diabetes; may spread systemically in ummmunocompromised Tinea: several types -captis: infection of the scalp -corporis: infection of the body, mainly non-hairy parts, ring worm -pedis: athlete's foot -urguium: infection of the nails' particularly toenails

Herpes Simplex

Most common cold sore/ fever blisters (herpes-1) Genital Herpes (herpes-2) Both types have similar effect Primary infections may be asymptomatic: virus remains in latent in sensory nerve ganglia Reoccurrence may be triggered by common cold, sun exposure, stress Spread from direct contact with fluid Potential Complications: spread to eye, spread to nail bed

Kaposi's Sarcoma

Occurs in AIDS and other immune deficiencies May affect viscera as well as skin Malignant cells arise from endothelium in small blood vessels: purplish macule, nonpruritic, nonpainful

Other Infections

Scabies: invasion of mites; females burrow in epidermis and lay eggs, male dies after fertilizing females, female dies after laying eggs, larvae migrate to skin surface but then burrow again for nutrients, very pruritic Pediculosis (lice): females lay eggs on hair shaft, after hatching lice bites host sucking blood for production of ova; excoriation (wearing off of skin) results from itching -Pediculus humanus corporis: body louse -captis: head louse -pubis: crabs, pubic lice