Structure, Function, and Disorders of the Integument

Structure, Function, and Disorders of the Integument
Chapter 41 Structure, Function, and Disorders of the Integument Copyright © 2017, Elsevier Inc. All rights reserved.

Layers of the Skin (Cont.)
Copyright © 2017, Elsevier Inc. All rights reserved.

Layers of the Skin (Cont.)
Dermal appendages Nails Hair Sebaceous glands Eccrine and apocrine sweat glands Blood supply Papillary capillaries Copyright © 2017, Elsevier Inc. All rights reserved.

Clinical Manifestations of Skin Dysfunction
Primary Lesions Secondary Lesions Macule Papule Patch Plaque Wheal Nodule Tumor Vesicle Bulla Pustule Cyst Telangiectasia Scale Lichenification Keloid Scar Excoriation Fissure Erosion Ulcer Atrophy Copyright © 2017, Elsevier Inc. All rights reserved.

Pressure Ulcers Pressure ulcers result from any unrelieved pressure on the skin, causing underlying tissue damage Pressure Shearing forces Friction Moisture Copyright © 2017, Elsevier Inc. All rights reserved.

Pressure Ulcers (Cont.)
Stages 1. Nonblanchable erythema of intact skin 2. Partial-thickness skin loss involving epidermis or dermis 3. Full-thickness skin loss involving damage or loss of subcutaneous tissue 4. Full-thickness skin loss with exposure of muscle, bone, or supporting structures Copyright © 2017, Elsevier Inc. All rights reserved.

Stages (Cont.) Suspected deep tissue injury—discolored (purple or maroon) intact skin or blood-filled blister Unstageable—full-thickness tissue loss with base of ulcer covered by slough or eschar, or both Preventive techniques Frequent skin assessment Repositioning Pressure reduction, removal, and distribution Elimination of moisture Copyright © 2017, Elsevier Inc. All rights reserved.

Keloids and Hypertrophic Scars
Elevated, rounded, and firm Clawlike margins that extend beyond the original site of injury Hypertrophic scars Elevated erythematous fibrous lesions that do not extend beyond the border of injury Both caused by excessive collagen formation during dermal connective tissue repair Copyright © 2017, Elsevier Inc. All rights reserved.

Pruritus Itching Multiple stimuli Associated with multiple primary skin disorders and systemic diseases Interaction with pain sensations Unmyelinated type C nerve fibers transmit itch sensations Copyright © 2017, Elsevier Inc. All rights reserved.

Disorders of the Skin Inflammatory disorders Eczema and dermatitis (used interchangeably) are the most common inflammatory disorders of the skin Characterized by Pruritus Lesions with indistinct borders Epidermal changes When chronic, the skin becomes thickened, leathery, and hyperpigmented from recurrent irritation and scratching Copyright © 2017, Elsevier Inc. All rights reserved.

Inflammatory Disorders
Allergic contact dermatitis Caused by T-cell–mediated or delayed hypersensitivity 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 Copyright © 2017, Elsevier Inc. All rights reserved.

Allergic Contact Dermatitis

Inflammatory Disorders
Irritant contact dermatitis Caused by activation of the innate immune system Severity related to concentration of the irritant, length of exposure, and disruption of the skin barrier Symptoms similar to allergic contact dermatitis Copyright © 2017, Elsevier Inc. All rights reserved.

Inflammatory Disorders (Cont.)
Atopic dermatitis Also called allergic dermatitis Associated with IgE antibodies Common with a history of hay fever or asthma Copyright © 2017, Elsevier Inc. All rights reserved.

Stasis dermatitis Occurs in the legs as a result of venous stasis and edema Sequence of events Erythema Pruritus Scaling Petechiae Hyperpigmentation Ulcerations Copyright © 2017, Elsevier Inc. All rights reserved.

Seborrheic dermatitis Chronic inflammation of the skin involving the scalp, eyebrows, eyelids, ear canals, nasolabial folds, axilla, chest, and back Cradle cap in infants Scaly, white, or yellowish plaques Copyright © 2017, Elsevier Inc. All rights reserved.

Stasis and Seborrheic Dermatitis

Papulosquamous Disorders
Psoriasis Chronic, relapsing, proliferative, inflammatory skin disorder Caused by complex interactions between macrophages, fibroblasts, dendritic cells, natural killer cells, T-helper, and regulatory T cells Copyright © 2017, Elsevier Inc. All rights reserved.

Papulosquamous Disorders (Cont.)
Psoriasis (Cont.) Shows evidence of dermal and epidermal thickening Epidermal turnover goes from 14 to 20 days to 3 to 4 days Cells do not have time to mature or adequately keratinize Silvery appearance Copyright © 2017, Elsevier Inc. All rights reserved.

Pityriasis rosea Benign, self-limiting inflammatory disorder Usually occurs during the winter months Herald patch Circular, demarcated, salmon-pink, 3- to 10-cm lesion Secondary lesions develop within 14 to 21 days and extend over the trunk and upper part of the extremities Copyright © 2017, Elsevier Inc. All rights reserved.

Lichen planus Benign autoimmune inflammatory disorder of the skin and mucous membranes T cells, adhesion molecules, inflammatory cytokines, perforin, and antigen-presenting cells involved Linked to numerous drugs and hepatitis C virus Nonscaling, purple-colored, flat-topped, polygonal, pruritic papules Oral lesions Pruritus is the most distressing symptom Copyright © 2017, Elsevier Inc. All rights reserved.

Pityriasis Rosea Herald Patch

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 Copyright © 2017, Elsevier Inc. All rights reserved.

Lupus erythematosus Systemic, inflammatory, autoimmune disease with cutaneous manifestations Discoid lupus erythematosus Restricted to the skin Photosensitivity Butterfly pattern over the nose and cheeks Related to genetic and environmental factors and an altered immune response Lesions persist for months and then resolve spontaneously or atrophy Copyright © 2017, Elsevier Inc. All rights reserved.

Discoid Lupus Erythematosus

Vesiculobullous Diseases
Pemphigus Rare, blister-forming disease of the skin and oral mucous membranes Autoimmune disease caused by circulating IgG autoantibodies The antibodies are against the cell surface adhesion molecule, desmoglein, in the suprabasal layer of the epidermis Immunofluorescence demonstrates the presence of antibodies at the site of blister formation Copyright © 2017, Elsevier Inc. All rights reserved.

Vesiculobullous Diseases (Cont.)
Pemphigus (Cont.) Types Pemphigus vulgaris (most common) Pemphigus vegetans Pemphigus foliaceus Pemphigus erythematosus Paraneoplastic pemphigus (severe) IgA pemphigus Pemphigus herpetiformis Copyright © 2017, Elsevier Inc. All rights reserved.

Vesiculobullous Diseases
Erythema multiforme Syndrome characterized by inflammation of the skin and mucous membranes Associated T-cell immunologic reactions to drugs or microorganisms Caused by immune complexes formed and deposited around dermal blood vessels, basement membranes, and keratinocytes Copyright © 2017, Elsevier Inc. All rights reserved.

Vesiculobullous Diseases (Cont.)
Erythema multiforme (Cont.) “Bull’s-eye” or target lesion Central erythematous region surrounded by rings of alternating edema and inflammation Affects the mouth, air passages, esophagus, urethra, and conjunctiva Severe forms Stevens-Johnson syndrome (bullous form) Toxic epidermal necrolysis Copyright © 2017, Elsevier Inc. All rights reserved.

Infections Bacterial infections Folliculitis Infection of hair follicle Furuncles Inflammation of hair follicles Carbuncles Collection of infected hair follicles Cellulitis Infection of the dermis and subcutaneous tissue Erysipelas Acute superficial infection of the upper dermis Impetigo Superficial lesion of the skin caused by coagulase-positive Staphylococcus or β-hemolytic streptococci Copyright © 2017, Elsevier Inc. All rights reserved.

Infections Viral infections Herpes simplex virus HSV-1 and HSV-2 Transmitted by contact with infected saliva Associated with oral infections or infection of the cornea, mouth, and orolabia—HSV-1 Lesions for HSV-1 appear as a rash or clusters of inflamed and painful vesicles Genital infections are more commonly caused by HSV-2 Copyright © 2017, Elsevier Inc. All rights reserved.

Infections Viral infections (Cont.) Herpes zoster (shingles) and varicella (chickenpox) Caused by the same herpesvirus—varicella-zoster virus (VZV) Primary infection followed years later by activation of the virus to cause herpes zoster (shingles) Virus remains latent in trigeminal and dorsal root ganglia Copyright © 2017, Elsevier Inc. All rights reserved.

Warts Benign lesions caused by the human papillomavirus (HPV) Common warts Common in children Usually on fingers Plantar warts Usually on pressure points on bottom of feet Condylomata acuminata Venereal warts Copyright © 2017, Elsevier Inc. All rights reserved.

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 manus (hand) Tinea pedis (athlete’s foot) Tinea corporis (ringworm) Tinea cruris (groin, jock itch) Tinea unguium (nails) or onychomycosis Copyright © 2017, Elsevier Inc. All rights reserved.

Fungal Infections Candidiasis Caused by Candida albicans Normally found on the skin, mucous membranes, 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 Copyright © 2017, Elsevier Inc. All rights reserved.

Vascular Disorders Cutaneous vasculitis Inflammation of the blood vessel wall Results from immune complexes in the small blood vessels Develops from drugs, allergens, or viral infections Lesions Palpable purpura progressing to hemorrhagic bullae with necrosis and ulceration Copyright © 2017, Elsevier Inc. All rights reserved.

Vascular Disorders (Cont.)
Urticaria Circumscribed area of raised erythema and edema of the superficial dermis Associated with type I hypersensitivity reactions to allergens Histamine release causes endothelial cells of the skin to contract Causes leakage of fluid from the vessels Most lesions resolve spontaneously within 24 hours, but new lesions may appear Copyright © 2017, Elsevier Inc. All rights reserved.

Scleroderma Localized or systemic Causes thickening (sclerosis) of the skin Associated with several antibodies Localized scleroderma is differentiated from the systemic form of the disease by the absence of sclerodactyly, Raynaud’s phenomenon, abnormalities of the nail-bed capillaries, or internal organ involvement CREST acronym Copyright © 2017, Elsevier Inc. All rights reserved.

Which of the following skin conditions is caused by a bacterial infection? Warts Varicella Impetigo Herpes simplex Correct Answer: C Impetigo is caused by Staphylococcus or Streptococcus. Warts are caused by human papillomavirus. Varicella (chickenpox) is caused by the same herpesvirus. Herpes simplex is caused by the herpes simplex virus. Copyright © 2017, Elsevier Inc. All rights reserved.

Ticks Lyme disease Multisystem inflammatory disease caused by the spirochete Borrelia burgdorferi transmitted by Ixodes tick bites Symptoms of the disease occur in three stages Localized infection Disseminated infection Late persistent infection Copyright © 2017, Elsevier Inc. All rights reserved.

Benign Tumors Seborrheic keratosis Benign proliferation of cutaneous basal cells Keratoacanthoma Benign, self-limiting tumor of squamous cell differentiation from hair follicles Actinic keratosis Premalignant lesion composed of aberrant proliferations of epidermal keratinocytes Nevi (moles or birthmarks) Benign pigmented or nonpigmented lesions Copyright © 2017, Elsevier Inc. All rights reserved.

Skin Cancer Basal cell carcinoma Squamous cell carcinoma Most common cancer in the world Numerous subtypes Grows slowly, often ulcerates, develop crusts, and is firm to the touch Metastasis is rare Tumor of the epidermis Second most common human cancer In situ or invasive Rarely invade surrounding tissue Copyright © 2017, Elsevier Inc. All rights reserved.

Squamous Cell Carcinoma

Skin Cancer Cutaneous melanoma Malignant tumor of the skin originating from melanocytes Most serious skin cancer Kaposi sarcoma Vascular malignancy associated with immunodeficiency Associated with human herpesvirus-8 (HHV-8) Pruritic, painful, purplish-brown lesions Copyright © 2017, Elsevier Inc. All rights reserved.

Skin Cancer Cutaneous lymphomas Cutaneous T-cell and B-cell lymphomas present in the skin without evidence of extracutaneous disease at the time of diagnosis Develop from clonal expansion of B cells, T helper cells, and rarely T suppressor cells Mycosis fungoides Copyright © 2017, Elsevier Inc. All rights reserved.

Which of the following skin conditions is benign? Kaposi sarcoma Actinic keratosis Basal cell carcinoma Cutaneous melanoma Correct Answer: B Actinic keratosis is a premalignant lesion. Kaposi sarcoma (KS) is a vascular malignancy associated with immunodeficiency states. Basal cell carcinoma is a malignant cancer of the skin. Cutaneous melanoma is a malignant tumor of the skin that originates from melanocytes. Copyright © 2017, Elsevier Inc. All rights reserved.

Burns First degree Epidermis only Local pain and erythema Second degree Superficial partial thickness Epidermis and some dermis Deep partial thickness Epidermis and dermis, leaving only skin appendages Third degree Full thickness Epidermis, dermis, and underlying subcutaneous tissue Copyright © 2017, Elsevier Inc. All rights reserved.

Superficial Partial-Thickness Burn

Deep Partial-Thickness Burn

Burns (Cont.) Fourth degree Full-thickness and deeper tissue Epidermis, dermis, and underlying subcutaneous tissue, tendons, muscle, and bone Total body surface area estimation Rule of nines Modified Lund and Browder chart Copyright © 2017, Elsevier Inc. All rights reserved.

Estimating Burn Injury

Burns (Cont.) >20% TBSA considered to be major burn injuries Associated with massive evaporative water losses and fluctuations of large amounts of fluid, electrolytes, and plasma proteins into the body tissues Burn shock Copyright © 2017, Elsevier Inc. All rights reserved.

Burns (Cont.) Cardiovascular and systemic response Hallmark of burn shock is decreased cardiac contractility and decreased cardiac output with inadequate capillary perfusion Fluid and protein movement out of the vascular compartment results in an elevated hematocrit and white blood cell count and hypoproteinemia Irreversible shock and death if not treated immediately Capillary seal Copyright © 2017, Elsevier Inc. All rights reserved.

Burns (Cont.) Cellular response to burn injury Transmembrane potential disruption Impairs the sodium-potassium pump Increased intracellular sodium and water Decreased potassium Copyright © 2017, Elsevier Inc. All rights reserved.

Burns (Cont.) Metabolic response to burn injury Flow phase Systemic hypermetabolic response Can persist for up to 2 years following a burn Inflammatory response with local activation and recruitment of inflammatory cells at the site of injury Hypermetabolism increases the thermal regulatory set point and core and skin temperatures Copyright © 2017, Elsevier Inc. All rights reserved.

Burns (Cont.) Immunologic response to burn injury Immediate, prolonged, and severe End result is immunosuppression Altered white blood cells Impaired phagocytosis Abnormal cellular and humoral immunity Potentially fatal wound sepsis Evaporative water loss Loss of the skin’s barrier function and ability to regulate evaporative water loss Skin and the lungs have increased loss of water as a result of hypermetabolism and hyperventilation Replacement is mandatory Copyright © 2017, Elsevier Inc. All rights reserved.

Burns (Cont.) Complex, prolonged recovery and complications with major burns Goal is wound débridement and closure in a manner that promotes survival Scar formation with contractures is often a consequence of healing in deep partial-thickness and third-degree burns Copyright © 2017, Elsevier Inc. All rights reserved.

Burns (Cont.) Elements of survival of major burn Provision of adequate fluids and nutrition Meticulous management of wounds with early surgical excision and grafting Aggressive treatment of infection or sepsis Promotion of thermoregulation Copyright © 2017, Elsevier Inc. All rights reserved.

Axillary Burn Scar Contracture

Hypertrophic Scarring

Cold Injury Skin injury caused by exposure to extreme cold Usually affects fingers, toes, ears, nose, and cheeks Frostnip Cold exposure without tissue freezing Reversible Skin pallor and numbness Chilblain Violaceous skin color with plaques or nodules, pain, and pruritus and without ice crystal formation Copyright © 2017, Elsevier Inc. All rights reserved.

Cold Injury (Cont.) Frostbite Occurs when tissues freeze slowly with ice crystal formation Numbness and no sensation of pain until thawing; then severe pain Classified by depth of injury Flash freeze Rapid cooling with intracellular ice crystals associated with contact with cold metals or volatile liquids Copyright © 2017, Elsevier Inc. All rights reserved.

Disorders of the Hair Alopecia Loss of hair from the head or body Androgenic alopecia Localized hair loss occurring in about 80% of men Genetically predisposed response to androgens Androgen-sensitive and androgen-insensitive follicles Copyright © 2017, Elsevier Inc. All rights reserved.

Disorders of the Hair (Cont.)
Female-pattern alopecia Progressive thinning and loss of hair over the central part of the scalp No loss of hair along the frontal hairline Copyright © 2017, Elsevier Inc. All rights reserved.

Disorders of the Hair (Cont.)
Alopecia areata Autoimmune T-cell–mediated inflammatory disease against hair follicles that results in hair loss Hirsutism Abnormal growth and distribution of hair on the face, body, and pubic area in a male pattern that occurs in women Androgen-sensitive areas Copyright © 2017, Elsevier Inc. All rights reserved.

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