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Structure, Function, and Disorders
of the Integument

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Layers of the Skin
 Epidermis
 Dermis
 Hypodermis

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Layers of the Skin (cont’d)

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Layers of the Skin (cont’d)
 Dermal appendages:
 Nails
 Hair
 Sebaceous glands
 Eccrine and apocrine sweat glands
 Blood supply
 Papillary capillaries

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Nails

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Aging and Skin Integrity
 The integumentary system reflects
numerous changes from genetic and
environmental factors
 The skin becomes thinner, drier, wrinkled, and
demonstrates a change in pigmentation
 Shortening and decrease in the number of
capillary loops
 Fewer melanocytes and Langerhans cells

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Aging and Skin Integrity (cont’d)
 The integumentary system reflects
numerous changes from genetic and
environmental factors (cont’d)
 Atrophy of the sebaceous, eccrine, and
apocrine glands
 Changes in hair color
 Fewer hair follicles and growth of thinner hair

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Clinical Manifestations of Skin
Dysfunction
 Macule
 Papule
 Patch
 Plaque
 Wheal
 Nodule
 Tumor
 Vesicle
 Bulla
 Pustule
 Cyst
 Telangiectasia
 Scale
 Lichenification
 Keloid
 Scar
 Excoriation
 Fissure
 Erosion
 Ulcer
 Atrophy

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Pressure Ulcers
 Pressure ulcers result from any unrelieved
pressure on the skin, causing underlying
tissue damage
 Pressure
 Shearing forces
 Friction
 Moisture

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Pressure Ulcers (cont’d)

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Pressure Ulcers (cont’d)
 Stages:
 I. Nonblanchable erythema of intact skin
 II. Partial-thickness skin loss involving
epidermis or dermis
 III. Full-thickness skin loss involving damage or
loss of subcutaneous tissue
 IV. Full-thickness skin loss with damage to
muscle, bone, or supporting structures

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Keloids
 Elevated, rounded, and firm
 Clawlike margins that extend beyond the
original site of injury
 Excessive collagen formation during
dermal connective tissue repair
 Common in darkly pigmented skin types
and burn scars
 Type III collagen is increased

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Keloids (cont’d)

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Pruritus
 Itching
 Most common symptom of primary skin
disorders
 Itch is carried by specific unmyelinated C-
nerve fibers and is triggered by a number
of itch mediators
 The CNS can modulate the itch response

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Pruritus (cont’d)
 Pain stimuli at lower intensities can induce
itching
 Chronic itching can result in infections and
scarring due to persistent scratching

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Disorders of the Skin
 Inflammatory disorders
 The most common inflammatory disorders of
the skin are dermatitis or eczema
 There are various types of dermatitis
 The disorders are generally characterized by:
• Pruritus
• Lesions with indistinct borders
• Epidermal changes

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Inflammatory Disorders
 Allergic contact dermatitis
 Caused by a hypersensitivity type IV reaction
 The allergen comes in contact with the skin,
binds to a carrier protein to form a sensitizing
antigen; Langerhans cells process the antigen
and carry it to T cells, which become sensitized
to the antigen
 Manifestations:
• Erythema
• Swelling
• Pruritus
• Vesicular lesions

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Allergic Contact Dermatitis

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Inflammatory Disorders
 Atopic dermatitis
 Type I hypersensitivity: activation of mast cells,
eosinophils, T-lymphocytes, and other
inflammatory cells
 Causes red, weeping crusts and chronic
inflammation, lichenification

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Inflammatory Disorders (cont’d)
 Irritant contact dermatitis
 Nonimmunologic inflammation of the skin
 Chemical irritation from acids or prolonged
exposure to irritating substances
 Symptoms similar to allergic contact dermatitis
 Treatment: remove stimulus

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Inflammatory Disorders (cont’d)
 Stasis dermatitis
 Occurs in the legs as a result of venous stasis,
edema, and vascular trauma
 Sequence of events:
• Erythema
• Pruritus
• Scaling
• Petechiae
• Ulcerations

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Inflammatory Disorders (cont’d)
 Seborrheic dermatitis
 Inflammation of the skin involving the scalp,
eyebrows, eyelids, nasolabial folds, and ear
canals
 Scaly, white, or yellowish plaques

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Stasis and Seborrheic Dermatitis

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Papulosquamous Disorders
 Psoriasis
 Chronic, relapsing, proliferative skin disorder
 T cell immune- mediated skin disease
 Scaly, thick, silvery, elevated lesions, usually
on the scalp, elbows, or knees caused by a
high rate of mitosis in the basale layer

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Papulosquamous Disorders
(cont’d)
 Psoriasis (cont’d)
 Shows evidence of dermal and epidermal
thickening
 Epidermal turnover goes from 26 to 30 days to
3 to 4 days
 Cells do not have time to mature or adequately
keratinize

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Psoriasis

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Papulosquamous Disorders
 Psoriasis (cont’d)
 Plaque psoriasis
 Inverse psoriasis
 Guttate psoriasis
 Pustular psoriasis
 Erythrodermic psoriasis

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Papulosquamous Disorders
(cont’d)

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Papulosquamous Disorders
(cont’d)
 Pityriasis rosea
 Benign, self-limiting inflammatory disorder
 Usually occurs during the winter months
 Herald patch
• Circular, demarcated, salmon-pink, 3- to 4-cm lesion

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Papulosquamous Disorders
(cont’d)

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Papulosquamous Disorders
(cont’d)
 Lichen planus
 Benign, inflammatory disorder of the skin and
mucous membranes
 Unknown origin, but T cells, adhesion
molecules, inflammatory cytokines, and
antigen presenting cells are involved
 Nonscaling, violet-colored, 2- to 4-mm lesions
 Wrists, ankles, lower legs, genitalia

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Lichen Planus

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Papulosquamous Disorders
 Acne vulgaris
 Inflammatory disease of the pilosebaceous
follicles
 Acne rosacea
 Inflammation of the skin that develops in
adulthood
 Lesions
• Erythematotelangiectatic, papulopustular,
phymatous, and ocular
• Associated with chronic, inappropriate vasodilation
resulting in flushing and sensitivity to the sun

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Papulosquamous Disorders
(cont’d)
 Lupus erythematosus
 Inflammatory, autoimmune disease with
cutaneous manifestations
 Discoid lupus erythematosus
• Restricted to the skin
• Photosensitivity
• Butterfly pattern over the nose and cheeks
 Systemic lupus erythematosus

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Discoid Lupus Erythematosus

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Vesiculobullous Disorders
 Pemphigus
 Rare, chronic, blister-forming disease of the
skin and oral mucous membranes
 Blisters form in the deep or superficial
epidermis
 Autoimmune disease caused by circulating IgG
autoantibodies
• The antibodies are against the cell surface adhesion
molecule, desmoglein in the suprabasal layer of the
epidermis

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Vesiculobullous Disorders (cont’d)
 Pemphigus (cont’d)
 Tissue biopsies demonstrate autoantibody
presence
 Types:
• Pemphigus vulgaris (severe)
• Pemphigus foliaceus
• Pemphigus erythematosus

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Vesiculobullous Disorders (cont’d)
 Bullous pemphigoid
 More benign disease than pemphigus vulgaris
 Bound IgG and blistering of the subepidermal
skin layer
 Subepidermal blistering and eosinophils
distinguish pemphigoid from pemphigus

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Bullous Pemphigoid

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Vesiculobullous Disorders
 Erythema multiforme
 Acute, recurring disorder of the skin and
mucous membranes
 Associated with allergic or toxic reactions to
drugs or microorganisms
 Caused by immune complexes formed and
deposited around dermal blood vessels,
basement membranes, and keratinocytes

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Vesiculobullous Disorders (cont’d)
 Erythema multiforme (cont’d)
 “Bull’s-eye” or target lesion
• Erythematous regions surrounded by rings of
alternating edema and inflammation
 Bullous lesions form erosions and crusts when
they rupture
 Affects the mouth, air passages, esophagus,
urethra, and conjunctiva
 Severe forms:
• Stevens-Johnson syndrome (bullous form)
• Toxic epidermal necrolysis

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Infections
 Bacterial infections:
 Folliculitis
 Furuncles
 Carbuncles
 Cellulitis
 Erysipelas
 Impetigo

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Furuncle

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Infections
 Viral infections
 Herpes zoster and varicella

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Herpes Simplex Virus

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Warts
 Benign lesions caused by the human
papillomavirus (HPV)
 Diagnosed by visualization
 Condylomata acuminata
 Venereal warts

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Fungal Infections
 Fungi causing superficial skin lesions are
called dermatophytes
 Fungal disorders are called mycoses;
mycoses caused by dermatophytes are
termed tinea
 Tinea capitis (scalp)
 Tinea pedis (athlete’s foot)
 Tinea corporis (ringworm)
 Tinea cruris (groin, jock itch)
 Tinea unguium (nails) or onychomycosis

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Tinea Pedis

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Fungal Infections
 Candidiasis
 Caused by Candida albicans
 Normally found on the skin, in the GI tract, and in the
vagina
 Candida albicans can change from a commensal
organism to a pathogen
• Local environment of moisture and warmth
• Systemic administration of antibiotics
• Pregnancy
• Diabetes mellitus
• Cushing disease
• Debilitated states
• Age younger than 6 months
• Immunosuppression
• Neoplastic diseases

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Vascular Disorders
 Cutaneous vasculitis
 Results from immune complexes in the small
blood vessels
• Develops from drugs, bacterial infections, viral
infections, or allergens
 Lesions
• Palpable purpura progressing to hemorrhagic bullae
with necrosis and ulceration

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Vascular Disorders (cont’d)
 Urticaria
 Caused by type I hypersensitivity reactions to
allergens
 Histamine release causes endothelial cells of
the skin to contract
• Causes leakage of fluid from the vessels
 Treatment
• Antihistamines and steroids

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Vascular Disorders (cont’d)
 Scleroderma
 Sclerosis of the skin that can progress to the
internal organs
 The disease is associated with several
antibodies
 Lesions exhibit massive deposits of collagen
with inflammation, vascular changes, and
capillary dilation
 Skin is hard, hypopigmented, taut, and tightly
connected to underlying tissue

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Vascular Disorders (cont’d)
 Scleroderma (cont’d)
 Facial skin becomes very tight
 Fingers become tapered and flexed; nails and
fingertips can be lost from atrophy
 Mouth may not open completely
 50% of patients die within 5 years

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Scleroderma

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Insect Bites
 Bees
 Mosquitoes
 Flies

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Benign Tumors
 Seborrheic keratosis
 Keratoacanthoma
 Actinic keratosis
 Nevi (moles)

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Seborrheic Keratosis

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Cancer
 Basal cell carcinoma
 Squamous cell carcinoma
 Malignant melanoma
 Kaposi sarcoma

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Basal Cell Carcinoma

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Squamous Cell Carcinoma

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Malignant Melanoma

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Kaposi Sarcoma

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Burns
 Partial-thickness burns
 First degree
 Superficial and deep partial
 Second degree
 Full-thickness burns
 Third degree
 “Rule of nines”

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Superficial Partial-Thickness Burn

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Axillary Burn Scar Contracture

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Deep Partial-Thickness Burn

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Full-Thickness Burn

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Estimating Burn Injury

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Burns

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Hypertrophic Scarring

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Cultured Epithelial Autograft

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Frostbite
 Skin injury caused by exposure to extreme
cold
 Usually affects fingers, toes, ears, nose,
and cheeks
 The “burning reaction” is caused by
alternating cycles of vasoconstriction and
vasodilation
 Inflammation and reperfusion are both part
of the pathophysiology

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Disorders of the Hair
 Male-pattern alopecia
 Genetically predisposed response to
androgens
 Androgen-sensitive and androgen-insensitive
follicles

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Disorders of the Hair (cont’d)
 Female-pattern alopecia
 Associated with elevated levels of the serum
adrenal androgen dehydroepiandrosterone
sulfate
 No loss of hair along the frontal hairline

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Disorders of the Hair (cont’d)
 Alopecia areata
 Autoimmune T cell-mediated inflammatory
disease against hair follicles that results in
baldness
 Hirsutism
 Androgen-sensitive areas
• Abnormal growth and distribution of hair on the face,
body, and pubic area in a male pattern that occurs in
women

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Disorders of the Nail
 Paronychia
 Acute or chronic infection of the cuticle
 Onychomycosis
 Fungal or dermatophyte infection of the nail
plate