Skin Chapter Goals

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Chapter 16: Skin

 Find this out on page 650 in your book:

 What the name for the system that includes skin?  How much does our skin weigh?  How much surface area does it cover?

Copyright © 2011, 2008, 2005 by Saunders, an imprint of Elsevier Inc. All rights reserved.
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Chapter Goals

 Name the layers of the skin and the accessory structures associated with the skin.

 Build medical words using the combining forms that are related to the specialty of dermatology.

 Identify lesions, signs, and symptoms, and pathologic conditions that relate to the skin.

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Chapter Goals

 Describe laboratory tests and clinical procedures that pertain to the skin and recognize relevant abbreviations.

 Apply your new knowledge to understanding medical terms in their proper contexts, such as medical reports and records.

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Introduction

● the skin and its accessory structures (hair, nails and glands) make up the integumentary system of

the body
● weighs 8-10 lb ● covers 22 square feet

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Functions of Skin

 provides protective membrane - guards the deeper tissues against excessive loss of water, salts and heat - protects against pathogens

 glands lubricate and cool the skin

 receptor for sensations (pain, temp, pressure and touch)

 helps maintain body temperature

(thermoregulation)

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Anatomy of the Skin

Epidermis: outermost, thin cellular membrane - contains keratin

Dermis: dense, fibrous, connective tissue layer - contains collagen

Subcutaneous tissue (hypodermis): thick, fat-

containing tissue

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Acessory Organs of the Skin

HAIR: cells filled with the hard protein; keratin

 Hair follicles: shafts that hold the hair

 Five million hairs on body; 100,000 on head  Melanocytes at the root form the color  Grow .5 inch (1.3 cm) per month  Cutting does not affect growth

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Accessory Organs of the Skin
(cont’d)

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Accessory Organs of Skin
(cont’d)

NAILS: hard keratin

plates covering toes and fingers

 lunula  cuticle  paronychium

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(cont’d)

GLANDS: sebaceous and sweat

 Sebaceous glands secrete oily sebum into hair follicle to lubricate.

 Sweat glands secrete into pores to moisten and cool.

 Both are subject to bacterial growth.

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(cont’d)

 Sebaceous gland:

 Oil secreting gland in the dermis that is associated with hair follicles

 Eccrine sweat gland:

 Most numerous sweat producing exocrine gland

 Apocrine sweat gland.

 Sweat gland located in the axilla (armpit) and genital areas

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Colors – combining forms

● memorize this table

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Skin Pathology

CUTANEOUS LESIONS

● a lesion is an area of abnormal tissue anywhere on the body - it may be caused by trauma or disease

crust - collection of dried serum and cellular debris (scab, eczema, impetigo, seborrhea)

cyst - thick-walled, closed sac / pouch containing fluid or semisolid material

erosion - wearing away of the epidermis (dermoepidermal junction) - occur due to inflammation

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or injury

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Skin Pathology

fissure - grove or crack-like sore macule - flat lesion < 1cm in diameter (freckles, tattoo marks, flat moles)

nodule - solid, round or oval elevated lesion > 1cm in diameter (enlarge lymph node or solid growths)

papule - small (< 1cm), solid elevation of the skin (pimples - if confluent called plaques)

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Skin Pathology

polyp - growth extending from the surface of a mucous membrane (type of papule commonly found in nose / sinuses, colon, bladder and uterus)

pustule - papule containing pus (small abscess) ulcer - open sore on the skin or mucous membranes (deeper than an erosion)

vesicle - small collection (papule) of clear fluid (serum); blister (vesicles form in burns, allergies, dermatitis)

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Skin Pathology

wheal - smooth, edematous (swollen) papule or plaque that is redder or paler than the surrounding skin (often accompanied by itching and are seen in hives, anaphylaxis and insect bites)

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Cutaneous Lesions (p 662)

1. Crust 2. Cyst 3. Erosion 4. Fissure 5. Macule 6. Nodule 7. Papule 8. Polyp 9. Pustule 10.Ulcer 11.Vesicle 12.Wheal

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Signs and Symptoms

alopecia: absence of hair where it normally grows

 alopecia or baldness may be hereditary (male pattern baldness) or it may be caused by disease, injury or treatment (chemotherapy)
 alopecia areata - autoimmune disease - hair falls out in patches without scarring or inflammation

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ecchymosis: blue-black marks (bruise) on the skin

 caused by hemorrhages into the skin from injury or spontaneous leaking of blood from vessels

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petechia: small pinpoint hemorrhage

 smaller versions of ecchymoses - both ecchymoses and petechiae are forms of purpura (bleeding into the skin)

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pruritus - itching

 symptom associated with most forms of dermatitis  arises from stimulation of the nerves in the skin

urticaria: acute allergic reaction with red, round wheals on skin

 commonly due to food allergies (shelfish and strawberries)  localized edema occurs as well

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ABNORMAL CONDITIONS

acne: papular and pustular eruption of skin with increased production of sebum

 acne vulgaris (ordinary) is a buildup of sebum and keratin in the pores of the skin

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burns: injury to tissue due to heat, chemical, electric shock, lightning or radiation.

 first-degree burn - superficial epidermal lesions,

erythema, hyperesthesia and no blisters

 second-degree burn (partial thickness) - epidermal and

dermal lesions, erythema, blisters and hyperesthesia

second degree burn

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burns: injury to tissue due to heat, chemical, electric shock, lightning or radiation

 third-degree burns (full thickness) - epidermis and dermis are destroyed (necrosis) and subcutaneous layer damaged, leaving charred, white tissue

third degree burn

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 cellulitis: diffuse acute infection of skin marked by local heat, redness, pain and swelling

 abscess formation and tissue destruction can occur without appropriate antibiotic therapy

 eczema: inflammation of skin with erythematous, papulovesicular lesions caused by allergy

 chronic or acute atopic dermatitis is accompanied by pruritus
 treatment usually corticosteriods

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 exanthematous viral diseases: rash (exanthem) of

the skin due to virus

 examples: rubella (German measles), rubeola (measles) and varicella (chicken pox)

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 gangrene: death of tissue associated with loss of blood supply

 ischemia from injury, inflammation, frostbite, diabetes or arteriosclerosis can lead to necrosis followed by bacterial infection and putrefaction

 impetigo: bacterial inflammatory skin disease characterized by vesicles, pustules and crusted-over lesions

 contagious pyoderma caused by Staphylococci or
Streptococci
 treatment with systemic antibiotics and cleaning lesions

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 psoriasis: chronic recurrent dermatosis marked by itchy, scaly, red plaques covered by silvery gray scales

 not infectious or contagious but autoimmune - caused by in increased rate of growth of the basal layer of epidermis

 scabies: contagious, parasitic infection (mites) of the skin with intense pruritus

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 scleroderma: chronic, progressive disease of skin and internal organs with hardening and shrinking of connective tissue (autoimmune)

 fibrous, scar-like tissue forms in the skin, heart, lungs, kidneys and esophagus

 palliative treatment - immunosuppressives / antiinflammatory agents, physical therapy
 immunosuppressives

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 systemic lupus erythematosus (SLE): chronic

autoimmune disease of collagen in the skin, joints and internal organs

 “butterfly” pattern of redness over cheeks and nose  primarily affects females  treatment includes corticosteroids and

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 tinea - infection of the skin caused by a fungus

 tinea corporis (ringworm) - infection is in a ring-like pattern
- highly contagious with severe pruritis

 tinea pedis (athletes foot), tinea capitis (scalp),tinea barbae
(under the beard), tinea unguiun (nails)

 treatment with antifungal agents

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vitiligo: loss of pigment (depigmentation) in areas of skin (milk-white patches)

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SKIN NEOPLASMS - BENIGN

callus - increased growth of cells in the keratin layer of the epidermis caused by pressure or friction

keloid - hypertrophied, thickened scar developing after trauma or surgical incision

 excessive collagen formation in the skin during connective tissue repair

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SKIN NEOPLASMS - BENIGN

 keratosis: thickened and rough lesion of the epidermis - associated with aging or skin dammage

 leukoplakia: white thickened patches of the mucous membrane tissue of the tongue or cheek

 nevus: pigmented lesion of the skin (moles)

 dysplastic nevi - moles with atypical cells that may progress to skin cancer

 verruca: epidermal growth (wart)

caused by a virus

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SKIN NEOPLASMS - MALIGNANT

basal cell carcinoma - malignant tumor of the basal

cell layer of the epidermis

 most frequent type of skin cancer  slow growing tumor - chronically sun-exposed skin  almost never metastasizes  treatment - surgical removal

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squamous cell carcinoma - malignant tumor of the

squamous epithelial cells in the epidermis

● tumors may grow anywhere there is squamous epithelium
(mouth, larynx, bladder, esophagus, lungs)
● treatment - surgical removal, cryotherapy, electrodesiccation or radiotherapy

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malignant melanoma - cancerous growth composed

of melanocytes

● genetic predisposition combined with exposure to ultraviolet light

● usually begins as a mottled, light brown to black macule with irregular borders - lesion may turn shades of red, blue, white and may crust and bleed
● often arise from preexisting moles (dysplastic nevi) and frequently appear on upper back, lower legs, arms and neck

● biopsy required to confirm diagnosis ● melanomas can metastasize to lung, liver, bone and brain ● treatment - excision, regional lymphadenectomy, chemotherapy / immunotherapy or radiotherapy

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SkinNeoplasms — Cancerous (cont’d)

the ABCDs of malignant melanoma.

A. asymmetry
B. border irregular

or circumscribed

C. color

varies from one area to another

D. Diameter

usually larger than 6mm

shades of brown, black (white, red, blue)

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