Structure, Function, and Disorders of the Integument

1. Structure, Function, and Disorders of the Integument Chapter 39

2. Layers of the Skin Epidermis Dermis Hypodermis

3. Layers of the Skin (cont’d)

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

5. Nails

6. 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

7. 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

8. 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

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

10. Pressure Ulcers (cont’d)

11. 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

12. 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

13. Keloids (cont’d)

14. 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

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

16. 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

17. 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

18. Allergic Contact Dermatitis

19. 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

20. 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

21. 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

22. 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

23. Stasis and Seborrheic Dermatitis

24. 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

25. 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

26. Psoriasis

27. Papulosquamous Disorders Psoriasis (cont’d) Plaque psoriasis Inverse psoriasis Guttate psoriasis Pustular psoriasis Erythrodermic psoriasis

28. Papulosquamous Disorders (cont’d)

29. 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

30. Papulosquamous Disorders (cont’d)

31. 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

32. Lichen Planus

33. 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

34. 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

35. Discoid Lupus Erythematosus

36. 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

37. Vesiculobullous Disorders (cont’d) Pemphigus (cont’d) Tissue biopsies demonstrate autoantibody presence Types: Pemphigus vulgaris (severe) Pemphigus foliaceus Pemphigus erythematosus

38. 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

39. Bullous Pemphigoid

40. 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

41. 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

42. Infections Bacterial infections: Folliculitis Furuncles Carbuncles Cellulitis Erysipelas Impetigo

43. Furuncle

44. Infections Viral infections Herpes zoster and varicella

45. Herpes Simplex Virus

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

47. 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

48. Tinea Pedis

49. 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

50. 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