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CHPT 8-Skin Disorders canvas ppt

Functions of the Skin

  • Acts as first line of defense when unbroken.

  • Prevents excessive fluid loss.

  • Controls body temperature through:

    • Cutaneous vasodilation

    • Secretion and evaporation of sweat

  • Active in sensory perception.

  • Important defense against environmental hazards.

  • Synthesizes vitamin D on exposure to small amounts of ultraviolet light.

Review of Normal Skin

  • Layers of the skin:

    • Epidermis—avascular (has 5 layers)

    • Dermis

    • Subcutaneous tissue (hypodermis)

Layers of the Epidermis

  • Stratum basale

    • Mitotic activity

  • Stratum spinosum

    • Cells connected by desmosomes

    • Protein synthesis

  • Stratum granulosum

    • Keratin formation begins

  • Stratum lucidum

    • Clear layer, keratinocytes degenerate here

    • Has Eleidin which later transforms to Keratin

  • Stratum corneum

    • Waterproofing barrier

Skin Cells

  • Keratin

    • Waterproofing of the skin

  • Melanin

    • Skin pigment—determines skin color

    • Production depends on multiple genes and environment

  • Albinism

    • Lack of melatonin production

  • Vitiligo

    • Small areas of hypopigmentation

  • Melasma

    • Patches of darker skin

Dermis

  • Connective tissue

    • Contains elastic and collagen fibers

    • Flexibility and strength of the skin

  • Contains nerves and blood vessels

    • Includes sensory receptors for:

      • Pressure

      • Touch

      • Pain

      • Heat

      • Cold

Appendages of the Skin

  • Nails

  • Hair follicles

    • Stratum basale—hair-producing

    • Arrector pili muscle associated with hair follicle

  • Sebaceous glands

    • Produce sebum

      • Secretion increases at puberty—influence of sex hormones

  • Sweat glands

    • Eccrine—all over body

    • Apocrine

      • Axillae, scalp, face, external genitalia

Hypodermis

  • Beneath dermis

    • Connective tissue

    • Fat cells

    • Macrophages

    • Fibroblasts

    • Larger blood vessels

    • Nerves

Resident (Normal) Flora of the Skin

  • Mixed flora—components differ in various areas of the body.

  • Microbes also reside under the fingernails, in hair follicles, and in glands.

  • Opportunistic infections may occur because of injury or other inflammatory lesion.

  • Infection may spread systemically from skin lesions.

Skin Lesions

  • The physical appearance of the lesion is necessary to make a diagnosis.

  • Skin lesions may be caused by:

    • Systemic disorders, e.g. Liver disease

    • Systemic infections, e.g. Chickenpox

    • Allergies to ingested food or drugs

    • Localized factors, e.g. exposure to toxins

  • 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 (itching)

    • Review Table 8-1

Common Skin Lesions

  • Macule: flat, circumscribed

  • Papule: small, solid elevation

  • Nodule: firm, raised, deep

  • Pustule: raised, often with a "head," filled with exudate or "pus"

  • Vesicle or blister: thin wall, raised, fluid filled

  • Ulcer: cavity in tissue

  • Plaque: Slightly elevated, flat, "scale"-like lesion

  • Fissure: crack in tissue

Pruritus

  • Associated with:

    • Allergic responses

    • Chemical irritation caused by insect bites

    • Infestations by parasites (e.g., scabies)

  • Mechanism not totally understood

    • Release of histamine in a hypersensitivity response causes marked pruritus

    • Infection may result from breaking the skin barrier caused by scratching

Contact Dermatitis (Type IV)

  • Exposure to an allergen

    • Metals, cosmetics, soaps, chemicals, plants

    • Sensitization occurs on first exposure.

    • Pruritic rash develops at site a few hours after exposure.

  • Direct chemical or mechanical irritation

    • Does not involve immune response

    • Is inflammatory because of direct exposure

      • Removal of irritant

      • Reduction of inflammation with topical glucocorticoids

Pathophysiology of Contact Dermatitis

  • Sensitization occurs on first exposure

  • Subsequent exposure results in manifestations, i.e. pruritic rash

  • Location of lesions is clue to identity of the allergen, i.e. poison ivy

  • Signs and Symptoms:

    • Pruritic area

    • Erythematous area

    • Edematous area

    • Area often covered with small vesicles

  • Chemical Irritation Manifestation

    • Edematous area

    • Erythematous area

    • May be pruritic or painful

Uticaria

  • Pathophysiology:

    • Result of type I hypersensitivity

      • Ingestion of substances

        • Examples: shellfish, drugs, certain fruits

  • Signs and Symptoms:

    • Eruption of hard, raised, erythematous lesion

    • Lesions are highly pruritic

    • Found:

      • Skin

      • May be scattered all over body

      • Occasionally in pharyngeal mucosa

        • Airway obstruction

Atopic Dermatitis (Eczema)

  • Atopic—inherited tendency (Type I)

  • Common problem in infancy

    • Rash is erythematous, with serous exudate.

    • Commonly occurs on face, chest, and shoulders

  • In adults, rash is dry, scaly, and pruritic, often on flexor surfaces.

  • Pathophysiology

    • Chronic inflammation results from response to allergens.

      • Eosinophilia and increased serum IgE levels

    • Affected areas become sensitive to irritants:

      • Soaps

      • Certain fabrics

      • Temperature changes

    • Potential complication

      • Secondary infections due to scratching

Psoriasis

  • Chronic inflammatory skin disorder

  • Autoimmune disease

  • Affects 1 – 3% of the population

  • Believed to be genetic in origin

  • Pathophysiology:

    • Onset usually in the teenage years

    • Marked by remission and exacerbations

    • Cases vary in severity

    • Results from abnormal T cell activation.

      • Excessive proliferation of keratinocytes

      • Cellular proliferation is greatly increased leading to thickening of the dermis and epidermis

      • Shedding occurs in one day rather than two week intervals

  • Signs and Symptoms

    • Red patches of skin covered with silvery scales

    • Small scaling spots (commonly seen in children)

    • Dry, cracked skin that may bleed

    • Itching, burning or soreness

    • Thickened, pitted or ridged nails

    • Swollen and stiff joints

    • (Can affect multiple organs)

Pemphigus

  • Autoimmune disorder

  • Mainly two forms

    • Pemphigus vulgaris (mucosal)

    • Pemphigus foliaceous (Skin)

  • Severity varies among individuals

  • Autoantibodies disrupt 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., Stevens-Johnson syndrome)

  • Signs and Symptoms

    • Blisters in mouth

    • Blisters spreading to the skin

    • Blisters are painful but not pruritic

    • Breathing difficulty due to swollen mouth and throat

Scleroderma

  • May occur as skin disorder

  • May be systemic and affect viscera

  • Primary cause unknown

  • Pathophysiology:

    • Increased collagen deposition

    • Inflammation and fibrosis with decreased capillary networks

    • May cause renal failure, intestinal obstruction, respiratory failure caused by distortion of tissues

  • Signs and Symptoms:

    • Hard, shiny, tight, immovable areas of skin

    • Fingertips narrowed and shortened

      • Raynaud's phenomenon may be present (lack of blood flow to toes and fingers)

    • Facial expression is lost

      • Skin tightens, movement of the mouth and eyes may be impaired

    • The cutaneous form may also affect the microcirculation of various organs, eventually causing renal failure, intestinal obstruction, or respiratory failure due to pulmonary hypertension.

Dupuytrens Contracture

  • Pathophysiology

    • Progressive hand deformity

    • Cause is unknown

    • Knots of tissue under skin of palms

    • Fingers eventually pulled into bent position

Skin Infections

  • May be caused by bacteria, viruses, fungi, other types of microbes, parasites

  • Caused by opportunistic microbes

  • Minor abrasions or cuts

  • Serious infections may develop.

  • Causative organism needs to be identified for appropriate treatment

  • Bacterial Infections:

    • Primary

      • Often caused by resident flora

    • Secondary

      • Developing in wounds or pruritic lesions

Cellulitis (erysipelas)

  • Infection of the dermis and subcutaneous tissue

  • Usually secondary to an injury

  • Causative organism

    • Usually Staphylococcus aureus

    • Sometimes Streptococcus

    • Frequently in lower trunks and legs

      • Especially in individuals with restricted circulation in the extremities; also in immunocompromised individuals

    • Area becomes red, swollen, and painful

    • Red streaks may develop, running along lymph vessels proximal to infected area

  • Signs and Symptoms

    • Reddened area

    • Edematous (swollen)

    • Pain

    • Red streaks along the lymph vessels proximal to the infected area

Furuncules (boils)

  • Usually caused by S. aureus

  • Begins 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.

Impetigo

  • Common infection in infants and children

    • May also occur in adults

    • S. aureus—highly contagious in neonates

  • Lesions commonly on face

  • Transmission may occur through close physical contact or through fomites

  • Pruritus common

    • Leads to scratching and further spread of infection

  • Signs and Symptoms

    • Small red vesicles, which rapidly enlarge

    • Vesicles rupture forming yellowish-brown crusty masses

    • Additional vesicles develop around the primary site by autoinoculation with hands, towels, or clothes

    • Pruritus is common, leading to scratching and further spread of infection

Acute Necrotizing Fasciitis

  • Fascia is the connective tissue that surrounds the blood vessels/nerve and muscles

  • Mixture of aerobic and anaerobic bacteria usually at site of infection

  • Severe inflammation and tissue necrosis

    • Usually caused by virulent strain of gram-positive, group A beta-hemolytic Streptococcus

    • Bacteria secrete toxins that break down fascia and connective tissue, causing massive tissue destruction.

  • Often a history of minor trauma or infection in the skin and subcutaneous tissue of an extremity

  • Signs and Symptoms

    • Local S/S:

      • Infected area appears markedly inflamed

      • Very painful

      • Infected area rapidly increases in size

      • Dermal gangrene is apparent

    • Systemic S/S:

      • Fever

      • Tachycardia

      • Hypotension

      • Mental confusion and disorientation

      • Possible organ failure

Leprosy (Hansen’s Disease)

  • Caused by Mycobacterium leprae

  • Chronic disease classified into three major types

  • Clinical signs and symptoms vary.

    • Generally affects skin, mucous membranes, and peripheral nerves

    • Damage can lead to loss of limbs.

  • Mechanism of pathogenicity largely unknown

Herpes Simplex

  • Herpes simplex type 1 (HSV-1)

    • Most common cause of cold sores or fever blisters

  • Herpes simplex type 2 (HSV-2)—genital herpes

  • Both types of HSV cause similar effects.

  • Primary infection may be asymptomatic

    • Virus remains latent in sensory nerve ganglia.

  • Recurrence may be triggered by:

    • Common cold, sun exposure, stress

  • Spread by direct contact with fluid from lesion

  • Spread of infection to others possible prior to appearance of lesions

  • Potential complication:

    • Spread of virus to eye

      • Keratitis

    • Herpetic whitlow

      • Painful infection of the fingers

Verrucae (Warts)

  • Human papillomavirus (HPV) types 1 to 4

    • Frequently develop in children and young adults

  • Plantar warts are common.

  • Spreads by viral shedding of the skin surface

  • May resolve spontaneously with time

  • Genital warts (HPV types 6 and 11)

Fungal Infections (Mycoses)

  • Most are superficial

    • Candida infection is associated with diabetes.

    • May spread systemically in immunocompromised individuals

Tinea

  • Tinea capitis

    • Infection of the scalp

    • Common in school-age children

    • Erythema may be apparent.

  • Tinea corporis

    • Infection of the body, particularly of nonhairy parts

    • Round lesion with clear center (ringworm)

    • Pruritus may be present.

  • Tinea pedis

    • Athlete’s foot—involves the feet, particularly the toes

    • Associated with swimming pools and gymnasiums

    • May be part of normal flora that becomes opportunistic

    • Secondary bacterial infection may occur

  • Tinea unguium

    • Infection of the nails, particularly the toenails

      • Nails turn white, then brown.

      • Nail thickens and cracks.

      • Infection tends to spread to other nails.

Other Infections

  • Scabies

    • Invasion by mite Sarcoptes scabiei

    • Female burrows into epidermis

      • Lays eggs over a period of several weeks

      • Male dies after fertilizing the female

      • Female dies after laying the eggs.

    • Larvae migrate to skin surface.

      • Burrow into skin in search of nutrients

      • Intensely pruritic!

    • Larvae mature and cycle is repeated

    • Burrows appear on skin as tiny, light brown lines.

  • Pediculosis (lice)

    • Pediculus humanus corporis—body louse

    • Pediculus humanus capitis—head louse

    • Pediculus humanus pubis—pubic louse

    • Female lice lay eggs on hair shafts.

    • After hatching, louse bites human host, sucking blood for production of ova

    • Excoriations result from scratching.

Skin Tumors: Keratoses

  • Benign lesions usually associated with aging or skin damage.

  • Seborrheic keratoses

    • Proliferation of basal cells

      • Lead to oval elevation

      • May be smooth or rough

  • Actinic keratoses

    • On skin exposed to ultraviolet radiation

    • Commonly in fair-skinned persons

    • Lesion appears as pigmented, scaly patch

Warning Signs of Skin Cancer

  • A sore that does not heal

  • A change in shape, size, color, or texture of a lesion, especially an expanding, irregular circumference or surface

  • New moles or odd-shaped lesions that develop

  • A skin lesion that bleeds repeatedly, oozes fluid, or itches

Guidelines to Reduce Risk of Skin Cancers

  • Reducing sun exposure at midday and early afternoon

  • Covering up with clothing

    • Remaining in shade

    • Wearing broad-brimmed hats to protect face and neck

  • Applying sunscreen or sunblock

  • Protecting infants and children from exposure and sun damage to skin

Squamous Cell Carcinoma

  • Painless, malignant tumor of the epidermis

  • Lesions most commonly found on exposed areas of the skin but also in oral cavity

    • Face and neck

    • Base of tongue

  • Excellent prognosis when lesion is removed within reasonable time

  • Invasive type arises from premalignant condition.

Malignant Melanoma

  • Highly metastatic form of skin cancer

  • Develops in melanocytes

    • From a nevus (mole)

  • Often appear as multicolored lesion with irregular border

  • Grow quickly

  • Change in shape, color, size, texture

  • May bleed

The ABCD of Melanoma

  • Melanoma is suspected in any nevus that shows:

    • Change in appearance

    • Change in border

    • Change in color

    • Increase in diameter

Kaposi’s Sarcoma

  • Occurs in those with AIDS and other immunodeficiencies

  • May affect viscera as well as skin

  • Malignant cells arise from endothelium in small blood vessels

    • Purplish macules

    • Nonpruritic, nonpainful

  • In immunocompromised patients, lesions develop rapidly over upper body.

Functions of the Skin

  • Acts as first line of defense when unbroken, preventing pathogen entry and physical damage.

  • Prevents excessive fluid loss, maintaining hydration and electrolyte balance.

  • Controls body temperature through:

    • Cutaneous vasodilation: Increases blood flow to the skin surface, dissipating heat.

    • Secretion and evaporation of sweat: Cools the body as sweat evaporates.

  • Active in sensory perception:

    • Contains receptors for touch, pressure, pain, and temperature.

  • Important defense against environmental hazards:

    • UV radiation, pollutants, and mechanical irritants.

  • Synthesizes vitamin D on exposure to small amounts of ultraviolet light:

    • Essential for calcium absorption and bone health.

Review of Normal Skin

  • Layers of the skin:

    • Epidermis—avascular (has 5 layers):

      • Outermost layer, provides a waterproof barrier and creates our skin tone.

      • Relies on the dermis for nutrient supply.

    • Dermis:

      • Contains blood vessels, nerves, hair follicles, and glands.

      • Provides structural support and elasticity.

    • Subcutaneous tissue (hypodermis):

      • Adipose tissue for insulation and cushioning.

      • Contains larger blood vessels and nerves.

Layers of the Epidermis

  • Stratum basale:

    • Mitotic activity: Cell division to replenish skin cells.

    • Contains melanocytes that produce melanin.

  • Stratum spinosum:

    • Cells connected by desmosomes: Provides strength and flexibility.

    • Protein synthesis: Production of keratin and other proteins.

  • Stratum granulosum:

    • Keratin formation begins: Cells accumulate granules containing keratin.

    • Cells begin to die as they move away from nutrient source.

  • Stratum lucidum:

    • Clear layer, keratinocytes degenerate here

    • Has Eleidin which later transforms to Keratin

  • Stratum corneum:

    • Waterproofing barrier: Dead, flattened cells filled with keratin.

    • Protects against abrasion and penetration.

Skin Cells

  • Keratin:

    • Waterproofing of the skin: Provides a protective barrier.

    • Produced by keratinocytes.

  • Melanin:

    • Skin pigment—determines skin color

    • Production depends on multiple genes and environment

    • Protects against UV radiation.

  • Albinism:

    • Lack of melatonin production

    • Genetic condition resulting in absence of pigment in skin, hair, and eyes.

  • Vitiligo:

    • Small areas of hypopigmentation

    • Autoimmune condition causing loss of melanocytes.

  • Melasma:

    • Patches of darker skin

    • Often associated with hormonal changes, such as pregnancy.

Dermis

  • Connective tissue:

    • Contains elastic and collagen fibers

    • Flexibility and strength of the skin

    • Supports epidermis and provides structure.

  • Contains nerves and blood vessels:

    • Includes sensory receptors for:

      • Pressure

      • Touch

      • Pain

      • Heat

      • Cold

Appendages of the Skin

  • Nails:

    • Protective keratinized structures on fingers and toes.

  • Hair follicles:

    • Stratum basale—hair-producing

    • Arrector pili muscle associated with hair follicle

    • Hair provides insulation and protection.

  • Sebaceous glands:

    • Produce sebum

    • Secretion increases at puberty—influence of sex hormones

    • Lubricates skin and hair.

  • Sweat glands:

    • Eccrine—all over body

      • Regulates body temperature through perspiration.

    • Apocrine:

      • Axillae, scalp, face, external genitalia

      • Produce thicker sweat with pheromones.

Hypodermis

  • Beneath dermis

  • Connective tissue:

    • Fat cells: Provide insulation and energy storage.

    • Macrophages: Immune cells that engulf pathogens and debris.

    • Fibroblasts: Produce collagen and elastin.

    • Larger blood vessels

    • Nerves

Resident (Normal) Flora of the Skin

  • Mixed flora—components differ in various areas of the body.

    • Includes bacteria, fungi, and viruses.

  • Microbes also reside under the fingernails, in hair follicles, and in glands.

    • Serve as a reservoir for potential infections.

  • Opportunistic infections may occur because of injury or other inflammatory lesion.

    • Disruption of skin barrier allows entry of pathogens.

  • Infection may spread systemically from skin lesions.

    • Bacteria can enter the bloodstream and cause widespread infection.

Skin Lesions

  • The physical appearance of the lesion is necessary to make a diagnosis.

    • Distribution, size, shape, color, and texture are important.

  • Skin lesions may be caused by:

    • Systemic disorders, e.g. Liver disease

      • Manifestations of internal diseases on the skin.

    • Systemic infections, e.g. Chickenpox

      • Viral or bacterial infections causing skin eruptions.

    • Allergies to ingested food or drugs

      • Immune responses triggered by allergens.

    • Localized factors, e.g. exposure to toxins

      • Irritants or chemicals causing local skin reactions.

  • 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 (itching)

    • Review Table 8-1

Common Skin Lesions

  • Macule: flat, circumscribed

  • Papule: small, solid elevation

  • Nodule: firm, raised, deep

  • Pustule: raised, often with a "head," filled with exudate or "pus"

  • Vesicle or blister: thin wall, raised, fluid filled

  • Ulcer: cavity in tissue

  • Plaque: Slightly elevated, flat, "scale"-like lesion

  • Fissure: crack in tissue

Pruritus

  • Associated with:

    • Allergic responses

      • Histamine release causes itching.

    • Chemical irritation caused by insect bites

      • Irritants trigger inflammatory response.

    • Infestations by parasites (e.g., scabies)

      • Mites burrowing into skin cause intense itching.

  • Mechanism not totally understood

    • Release of histamine in a hypersensitivity response causes marked pruritus

    • Infection may result from breaking the skin barrier caused by scratching

      • Secondary bacterial infections common.

Contact Dermatitis (Type IV)

  • Exposure to an allergen

    • Metals, cosmetics, soaps, chemicals, plants

    • Sensitization occurs on first exposure.

    • Pruritic rash develops at site a few hours after exposure.

  • Direct chemical or mechanical irritation

    • Does not involve immune response

    • Is inflammatory because of direct exposure

      • Removal of irritant

      • Reduction of inflammation with topical glucocorticoids

Pathophysiology of Contact Dermatitis

  • Sensitization occurs on first exposure

  • Subsequent exposure results in manifestations, i.e. pruritic rash

  • Location of lesions is clue to identity of the allergen, i.e. poison ivy

  • Signs and Symptoms:

    • Pruritic area

    • Erythematous area

    • Edematous area

    • Area often covered with small vesicles

  • Chemical Irritation Manifestation

    • Edematous area

    • Erythematous area

    • May be pruritic or painful

Uticaria

  • Pathophysiology:

    • Result of type I hypersensitivity

    • Ingestion of substances

    • Examples: shellfish, drugs, certain fruits

  • Signs and Symptoms:

    • Eruption of hard, raised, erythematous lesion

    • Lesions are highly pruritic

    • Found:

      • Skin

      • May be scattered all over body

      • Occasionally in pharyngeal mucosa

        • Airway obstruction

Atopic Dermatitis (Eczema)

  • Atopic—inherited tendency (Type I)

  • Common problem in infancy

    • Rash is erythematous, with serous exudate.

    • Commonly occurs on face, chest, and shoulders

  • In adults, rash is dry, scaly, and pruritic, often on flexor surfaces.

  • Pathophysiology

    • Chronic inflammation results from response to allergens.

      • Eosinophilia and increased serum IgE levels

    • Affected areas become sensitive to irritants:

      • Soaps

      • Certain fabrics

      • Temperature changes

    • Potential complication

      • Secondary infections due to scratching

Psoriasis

  • Chronic inflammatory skin disorder

  • Autoimmune disease

  • Affects 1 – 3% of the population

  • Believed to be genetic in origin

  • Pathophysiology:

    • Onset usually in the teenage years

    • Marked by remission and exacerbations

    • Cases vary in severity

    • Results from abnormal T cell activation.

      • Excessive proliferation of keratinocytes

      • Cellular proliferation is greatly increased leading to thickening of the dermis and epidermis

      • Shedding occurs in one day rather than two week intervals

  • Signs and Symptoms

    • Red patches of skin covered with silvery scales

    • Small scaling spots (commonly seen in children)

    • Dry, cracked skin that may bleed

    • Itching, burning or soreness

    • Thickened, pitted or ridged nails

    • Swollen and stiff joints

    • (Can affect multiple organs)

Pemphigus

  • Autoimmune disorder

  • Mainly two forms

    • Pemphigus vulgaris (mucosal)

    • Pemphigus foliaceous (Skin)

  • Severity varies among individuals

  • Autoantibodies disrupt 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., Stevens-Johnson syndrome)

  • Signs and Symptoms

    • Blisters in mouth

    • Blisters spreading to the skin

    • Blisters are painful but not pruritic

    • Breathing difficulty due to swollen mouth and throat

Scleroderma

  • May occur as skin disorder

  • May be systemic and affect viscera

  • Primary cause unknown

  • Pathophysiology:

    • Increased collagen deposition

    • Inflammation and fibrosis with decreased capillary networks

    • May cause renal failure, intestinal obstruction, respiratory failure caused by distortion of tissues

  • Signs and Symptoms:

    • Hard, shiny, tight, immovable areas of skin

    • Fingertips narrowed and shortened

      • Raynaud's phenomenon may be present (lack of blood flow to toes and fingers)

    • Facial expression is lost

      • Skin tightens, movement of the mouth and eyes may be impaired

    • The cutaneous form may also affect the microcirculation of various organs, eventually causing renal failure, intestinal obstruction, or respiratory failure due to pulmonary hypertension.

Dupuytrens Contracture

  • Pathophysiology

    • Progressive hand deformity

    • Cause is unknown

    • Knots of tissue under skin of palms

    • Fingers eventually pulled into bent position

Skin Infections

  • May be caused by bacteria, viruses, fungi, other types of microbes, parasites

  • Caused by opportunistic microbes

  • Minor abrasions or cuts

  • Serious infections may develop.

  • Causative organism needs to be identified for appropriate treatment

  • Bacterial Infections:

    • Primary

      • Often caused by resident flora

    • Secondary

      • Developing in wounds or pruritic lesions

Cellulitis (erysipelas)

  • Infection of the dermis and subcutaneous tissue

  • Usually secondary to an injury

  • Causative organism

    • Usually Staphylococcus aureus

    • Sometimes Streptococcus

    • Frequently in lower trunks and legs

      • Especially in individuals with restricted circulation in the extremities; also in immunocompromised individuals

    • Area becomes red, swollen, and painful

    • Red streaks may develop, running along lymph vessels proximal to infected area

  • Signs and Symptoms

    • Reddened area

    • Edematous (swollen)

    • Pain

    • Red streaks along the lymph vessels proximal to the infected area

Furuncules (boils)

  • Usually caused by S. aureus

  • Begins 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.

Impetigo

  • Common infection in infants and children

    • May also occur in adults

    • S. aureus—highly contagious in neonates

  • Lesions commonly on face

  • Transmission may occur through close physical contact or through fomites

  • Pruritus common

    • Leads to scratching and further spread of infection

  • Signs and Symptoms

    • Small red vesicles, which rapidly enlarge

    • Vesicles rupture forming yellowish-brown crusty masses

    • Additional vesicles develop around the primary site by autoinoculation with hands, towels, or clothes

    • Pruritus is common, leading to scratching and further spread of infection

Acute Necrotizing Fasciitis

  • Fascia is the connective tissue that surrounds the blood vessels/nerve and muscles

  • Mixture of aerobic and anaerobic bacteria usually at site of infection

  • Severe inflammation and tissue necrosis

    • Usually caused by virulent strain of gram-positive, group A beta-hemolytic Streptococcus

    • Bacteria secrete toxins that break down fascia and connective tissue, causing massive tissue destruction.

  • Often a history of minor trauma or infection in the skin and subcutaneous tissue of an extremity

  • Signs and Symptoms

    • Local S/S:

      • Infected area appears markedly inflamed

      • Very painful

      • Infected area rapidly increases in size

      • Dermal gangrene is apparent

    • Systemic S/S:

      • Fever

      • Tachycardia

      • Hypotension

      • Mental confusion and disorientation

      • Possible organ failure

Leprosy (Hansen’s Disease)

  • Caused by Mycobacterium leprae

  • Chronic disease classified into three major types

  • Clinical signs and symptoms vary.

    • Generally affects skin, mucous membranes, and peripheral nerves

    • Damage can lead to loss of limbs.

  • Mechanism of pathogenicity largely unknown

Herpes Simplex

  • Herpes simplex type 1 (HSV-1)

    • Most common cause of cold sores or fever blisters

  • Herpes simplex type 2 (HSV-2)—genital herpes

  • Both types of HSV cause similar effects.

  • Primary infection may be asymptomatic

    • Virus remains latent in sensory nerve ganglia.

  • Recurrence may be triggered by:

    • Common cold, sun exposure, stress

  • Spread by direct contact with fluid from lesion

  • Spread of infection to others possible prior to appearance of lesions

  • Potential complication:

    • Spread of virus to eye

      • Keratitis

    • Herpetic whitlow

      • Painful infection of the fingers

Verrucae (Warts)

  • Human papillomavirus (HPV) types 1 to 4

    • Frequently develop in children and young adults

  • Plantar warts are common.

  • Spreads by viral shedding of the skin surface

  • May resolve spontaneously with time

  • Genital warts (HPV types 6 and 11)

Fungal Infections (Mycoses)

  • Most are superficial

    • Candida infection is associated with diabetes.

    • May spread systemically in immunocompromised individuals

Tinea

  • Tinea capitis

    • Infection of the scalp

    • Common in school-age children

    • Erythema may be apparent.

  • Tinea corporis

    • Infection of the body, particularly of nonhairy parts

    • Round lesion with clear center (ringworm)

    • Pruritus may be present.

  • Tinea pedis

    • Athlete’s foot—involves the feet, particularly the toes

    • Associated with swimming pools and gymnasiums

    • May be part of normal flora that becomes opportunistic

    • Secondary bacterial infection may occur

  • Tinea unguium

    • Infection of the nails, particularly the toenails

      • Nails turn white, then brown.

      • Nail thickens and cracks.

      • Infection tends to spread to other nails.

Other Infections

  • Scabies

    • Invasion by mite Sarcoptes scabiei

    • Female burrows into epidermis

      • Lays eggs over a period of several weeks

      • Male dies after fertilizing the female

      • Female dies after laying the eggs.

    • Larvae migrate to skin surface.

      • Burrow into skin in search of nutrients

      • Intensely pruritic!

    • Larvae mature and cycle is repeated

    • Burrows appear on skin as tiny, light brown lines.

  • Pediculosis (lice)

    • Pediculus humanus corporis—body louse

    • Pediculus humanus capitis—head louse

    • Pediculus humanus pubis—pubic louse

    • Female lice lay eggs on hair shafts.

    • After hatching, louse bites human host, sucking blood for production of ova

    • Excoriations result from scratching.

Skin Tumors: Keratoses

  • Benign lesions usually associated with aging or skin damage.

  • Seborrheic keratoses

    • Proliferation of basal cells

    • Lead to oval elevation

      • May be smooth or rough

  • Actinic keratoses

    • On skin exposed to ultraviolet radiation

    • Commonly in fair-skinned persons

    • Lesion appears as pigmented, scaly patch

Warning Signs of Skin Cancer

  • A sore that does not heal

  • A change in shape, size, color, or texture of a lesion, especially an expanding, irregular circumference or surface

  • New moles or odd-shaped lesions that develop

  • A skin lesion that bleeds repeatedly, oozes fluid, or itches

Guidelines to Reduce Risk of Skin Cancers

  • Reducing sun exposure at midday and early afternoon

  • Covering up with clothing

    • Remaining in shade

    • Wearing broad-brimmed hats to protect face and neck

  • Applying sunscreen or sunblock

  • Protecting infants and children from exposure and sun damage to skin

Squamous Cell Carcinoma

  • Painless, malignant tumor of the epidermis

  • Lesions most commonly found on exposed areas of the skin but also in oral cavity

    • Face and neck

    • Base of tongue

  • Excellent prognosis when lesion is removed within reasonable time

  • Invasive type arises from premalignant condition.

Malignant Melanoma

  • Highly metastatic form of skin cancer

  • Develops in melanocytes

    • From a nevus (mole)

  • Often appear as multicolored lesion with irregular border

  • Grow quickly

  • Change in shape, color, size, texture

  • May bleed

The ABCD of Melanoma

  • Melanoma is suspected in any nevus that shows:

    • Change in appearance

    • Change in border

    • Change in color

    • Increase in diameter

Kaposi’s Sarcoma

  • Occurs in those with AIDS and other immunodeficiencies

  • May affect viscera as well as skin

  • Malignant cells arise from endothelium in small blood vessels

    • Purplish macules

    • Nonpruritic, nonpainful

  • In immunocompromised patients, lesions develop rapidly over upper body.