W9. Ch.18. The Skin

Question 1

Skin layers image

Answer 1

Question 2

Important facts in understanding the skin

Answer 2

• the skin protects the body primarily by maintaining its own integrity. Intact, dry skin is best barrier.
• skin can be traumatized mechanically, chemically, or thermally, or by various forms of radiation
• effects of acute injury is distinct from chronic or repeat injury ex. sunburn vs. base tan
• skin is normally covered in bacteria which does not affect it (sacrophytic bacteria)
• Skin participates in immune reaction with foreign substances
• skin may be affected by metabolic or immune diseases
• skin can be hyper/hypo pigmentated
• skin is most common site of tumors on the human body - contantly exposed to carcinogens
• skin has a limited way of responding to injury

Question 3

Appearance of skin lesions (image)

Answer 3

Question 4

Skin Terminology

Answer 4

Macule: flat lesion measuring less than 2cm in diameter; not raised or depressed; primarily represent-ing a change in skin color. The best example is the freckle: a brown, pigmented spot.

• Patch—similar to a macule, but larger than 2cm in diameter. The best example is the skin rash that occurs in measles, a childhood viral disease.
• Papule—slightly elevated, small induration of the skin with a diameter of less than 1cm. Papules are the hallmark of eczema, which is usually caused by allergy

.•Nodule—similar to a papule but larger (1 to 5cm in diameter). Nevi, or moles, which are pigmented, slightly raised skin lesions, are the best examples of this.

• Tumor—nodule with a diameter exceeding 5cm. Such tumors may be benign or malignant.
• Vesicle—fluid-filled elevation of the epidermis mea-suring less than 1cm in diameter. Herpesvirus infec-tions produce vesicles on the border of the lips.
• Bulla—vesicles measuring more than 1cm in diam-eter. Burns can cause bullae, some of which are confluent and may cover large surfaces of the skin.
• Pustule—vesicle filled with pus. Impetigo, a bacterial infection of the skin that usually affects children, is a typical example.
• Ulcer—defect of the epidermis. Syphilitic chancre, which most often appears on the skin or mucosa of the genitals, is a good example.
• Crust—a skin defect that is covered with coagulated plasma or blood. Healed wounds are covered with crusts.
• Scales—keratin layers that cover the skin in flakes or sheets and that can easily be scraped away. Sebor-rheic dermatitis are relatively common skin diseases of unknown etiology that cause scaling of the skin.
• Squames—large scales. Ichthyosis, a congenital thick-ening of the skin, forms numerous squames.”

Question 5

Most common congential skin abnormality

Answer 5

• nevus - birthmark
• known as hamartomas- tumor like lesions composed of normal skin elements, arranged in an abnormal manner
• brown birthmarks - composed of melanocytes
• nevus-flammeus - port wine mark - small blood vessels on face

Question 6

Skin abnormality as a congential

Answer 6

• many skin diseases have a significant hereditary component
• ichthyosis- scales
• albinism- hypopigmentation
• epidermolysis bullosa- several conditions- blisters from rubbing or minor trauma. no tx.

Question 7

Skin and mechanical trauma

Answer 7

• catagorize by means of infliction
• blunt trauma - objects (ex. hammer)- contusion presenting as a bruise
• laceration- disruption of the skin and underlying tissue. Requires surgical tx., does not heal easily
• sharp trauma -knife or bullet

Question 8

Mechanical Trauma: Pressure Ulcers

Answer 8

• develop on skin overlying a bone pressing on firm external surface
• 2/3 of these develop on lower back, sacrum, or posterior side of pelvic bones
• usually on bedbound, decubitus ulcers
• 2-3 million people affected in usa and canada
• circulation, poor nutrition, sensory defects
• shearing, friction, moisture,
• best tx. is prevention

Question 9

Thermal injury: burns

Answer 9

• extent depends on mode of exposure, duration, temp., and anatomic site ex. palms are thicker than the face
• may be localized or widespread
• final clinical outcome depends on the depth of the burn, and how much of the body surface is affected

Question 10

How are burns graded?

Answer 10

• by establishing depth of skin injury
• 1st, 2nd, 3rd

Question 11

1st degree burns

Answer 11

• mildest form
• erythema and swelling
• spotty single cell necrosis and edema
• transitory, reversible, heal spontaneously

Question 12

2nd degree burns

Answer 12

• characterized by blisters involving epidermis
• hair folicles and skin adnexa in the dermis are spared
• epidermis heals from the edges of the blisters and from the epitheliu of the hair follicles without scarring

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Question 13

3rd degree burns

Answer 13

• full thickness burns
• cause massive necrosis of the entire epidermis and dermis
• variable degree of subq tissue and underlying soft tissue
• localized can heal spontaneously without prominent scarring
• large areas can not heal spontaneously and require specialized tx. including skin transplantation from other parts of the body (autograft), but also from unrelated donor (allograft).

Question 14

Rule of 9s image

Answer 14

Question 15

Burns: to estimate survival and tx.

Answer 15

• nb to estimate the body surface area that has burned
• rule of 9s
• 9% of total body surface area to burns affecting the head and to each of the upper body extremities, and 9% x2 to each lower extremity and to the frontal and posterior surface of the trunk
• any burn exceeding 9% must be tx. in burn unit
• with modern tx. pt.s may be saved, but have crippling consequences
• mortality from uncontrolled fluid losses and infection from denuded body surfaces

Question 16

Cold injuries

Answer 16

• usually less severe and life threatening than burns
• immesion foot: tissue injury as a result of non-freezing cold and moist environment. Small vessels stunned by cold, become permanently dilated and unable to regulate local blood flow. Venous stagnation occurs, contibutes to cooling of tissues and bluish color of skin. Skin necrosis in form of blisters and ulcers.
• frostbite: exposure to subfreezing temp. More rapid and pronouced than immersion foot injury. Any part, but fingers and toes most often. Recovery may occur, but with gangrene can be lost. Surgical resection of damaged tissue.

Question 17

Electrical injury

Answer 17

• contact with unprotected wires
• contact generates heat which burns, leaving linear marks around its path. Electric mark of blackened skin
• can affect deeper tissues and internal organs
• may cause death by interfering with electric conduction in the heart
• blood vessels- thrombosis and infarction

Question 18

Radiation injury: sunshine

Answer 18

-Sunshine:

acute exposure over short period leads to hyperemia. Prolonged causes sunburn, blister and peeling. Acute is 1st or 2nd degree thermal injury

chronic: damages the skin. results in accellerated aging of skin and tumors. Aging affects all layers, more brittle and less elastic, develops wrinkles, and tends to resist injury less. Wounds heal more slowly. UV light is carcinogenic, tumors often on face or arms. Common on people who work outdoors. Sailors, farmers, fair skinned at risk.

Question 19

Radiation Injury: Ionizing radiation

Answer 19

• short term exposure to xrays, not problematic. Long or repeated, or large doses of ionizing radiation can produce significant lesions.
• alpha particles are not large, and do not penetrate the skin. Beta particles can penetrate up to 1cm and cause epidermal changes. Gamma rays and xrays penetrate the skin and cause little damage.
• all radiation particles induce secondary ionization, therefore all ionizing particles should be considered potentially damaging
• short term high levels of radiation can induce necrosis
• long term exposure to small doses can be carcinogenic

Question 20

Primary Bacterial Skin Infections

Answer 20

• typically caused by puss forming bacteria, therefore called pyoderma
• most infections caused by coagulase-positive staphyloccoci and beta-hemolytic streprococci, which may produce superficial or deep lesions. MRSA is resistant to abx.
• impedico is a common superficial lesion usually caused by streprococci pyogenes or staphylococcus aureus. Characterized by superficial pustules that rupture, leaving behind honey colored scabs. Most often found in the face of small children. b/c they are itchy, they spread to other parts of the body or to playmates. Highly contageous, but responds to abx. no scarring.

Question 21

Primary skin infection: impetigo

Answer 21

-impedico is a common superficial lesion usually caused by streprococci pyogenes or staphylococcus aureus.

Characterized by superficial pustules that rupture, leaving behind honey colored scabs. M

ost often found in the face of small children. b/c they are itchy, they spread to other parts of the body or to playmates.

Highly contageous, but responds to abx. no scarring.

Question 22

Primary Skin infection: Folliculitis

Answer 22

• infection of the hair follicle, common in hairy areas such as beard
• caused by s.aureus, purulent exudate that fills follicle lumen. Extends to the perifollicular tissue to form a boil (furnuncle). If infection spreads, abscess can occur. Carbuncle is several hair follicles. Usually in neck, require abx. More common in men

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Question 23

Secondary bacterial skin infections

Answer 23

• develop at the site of another disease, or in wounds
• impede healing of primary disease
• eczema is always contaminated with bacteria. Tx. of skin diseases always includes some sort of abx.

Question 24

Bacterial skin infections: systemic

Answer 24

-systemic infections may spread to the skin through blood or lymphatics, or direct extension from the underlying tissue to the skin. More common in debilitated or immune compromised

Question 25

Fungal infections of the skin

Answer 25

• fungal infections are very common
• dermatophytes (fungal pathogens) tend to live in dead tissue such as kerratin, hair, nails and cause almost no inflammation to underlying skin.
• cause itching and discomfort, and predispose to secondary bacterial infection
• most common cause of superficial dermatophytoses are feet, head, nails, and intertriginous parts of the body such as groin or armpit. These lesions are called tinea or ringworm.
• other fungi includes candida albicans - common source of thrush in children

Question 26

Acne

Answer 26

• pathogenesis not fully understood
• hereditary, hormonal, cleanliness
• sex hormones (androgen) stimulate subacious glands. secretion of sebum, and promote of hyperkeratosis at the orifice of hair follicles, which bloack the discharge of sebum.
• stagnant sebum is colonized by aerobic bacteria, which forms comedones opened or closed (blackhead and whitehead)
• through action of bacterial lipases, fat of sebum is broken down to glycerin and free fatty acids, which upon release into tissues causes inflammation
• the entire follicle and surrounding connective tissue forms pustules or abscesses

Question 27

Eczema

Answer 27

• term to desribe many forms of chronic dermatitis
  characteristics: -non specific lesions (papules, edema, vesicles), skin lesions are uniformly accompanied by pruitis.

b/c itching, they become infected, scaling, oozing

• chronic inflammatory cell infiltrates in the dermis, blood vessel dilation, and edema
• exogenous:traced to a specific cause in the environment (irritants or allergens). ex. contact dermatitis, can be drug induced reactions
• endogenous: may have an identifyable cause, but mostly unknown. can be autoimmune such as lupus

Question 28

Sebborheic Dermatitis

Answer 28

• widespread chronic disease -10-20% of USA
• reddening,scaling, and itching of skin, especially nasolabial folds, eyebrows, upper chest
• leads to formation of dandruff
• topical steroids some relief, but does not treat the allergic nature of the disease

Question 29

Psoriasis

Answer 29

• most nb papiloscuamous disease, b/c it affects 1-2% of entire world, and is uncurable.
• mode of inheritance polygenic, not mandelian
• presents with slightly elevated papules and patches
• covered in silvery scales, parakeratotis surface layer
• knees and elbows most often
• also-nails and head
• r/t trauma and motional stress

Question 30

Epithelial tumors: names

Answer 30

• sebborrhetic keratosis
• basal cell carcinoma
• squamous cell carcinoma

Question 31

Seborrhetic Keratosis

Answer 31

• also called senile warts
• most common, benign epithelial tumor
• presenting as a brownish, single or multiple
• innoculous and should not be considered premalignant

Question 32

Basal Cell carcinoma

Answer 32

• most common malignant tumor of the epithelium
• low grade, does not metastasize, rarely causes death
• typically located on sun exposed skin, casually r/t to overexposure to sun
• slightly elevated lesions with a central depression that becomes bigger
  tx. with resection, radiotherapy

Question 33

Squamous cell Carcinoma

Answer 33

• invasive malignant tumor of the surface epithelium
• most often on sun exposed skin
• presents as flat plaque, small persistant ulcer, or slightly elevated keratotic plaque
• on sun exposed skin, often preceeded by a malignant, preinvasive stage of disease, actinic keratosis. A.K is also known as squamous cell carcinoma “one half”, since it has all the same characteristics, just no invasion of underlying tissue involvement. Also known as solar keratosis. Forms atrophic or inducated patches that have a rough or hyperkeratotic surface. THese progress to a more atypical lesion, squamous carcinoma in situ.
• carcinoma in situ involves all layers of epidermis. Called pre-invasive carcinoma, to distinguish from carcinoma which deris and epidermis is involved.

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Question 34

Most telltale signs of skin cancer

Answer 34

• persistant non-healing ulcer, containing friable bleeding tissue
• ulcer or nodule of irregular shape and indistinct margins
• ulcer surrounded by atrophic and keratotic skin typical of sunlight injury

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Question 35

Prognosis of squamous cell carcinoma

Answer 35

• less than 2% metastasize, more locally invasive
• pronosis depends on stage of disease… therefore nb to be diagnosed early
• non of clinical signs are diagnostic, therefore must do biopsy

Question 36

Neoplasms of the skin: image

Answer 36

Question 37

Pigmented Lesions: image

Answer 37

Question 38

Pigmented lesions; freckle and lentigo and nevus

Answer 38

Freckle: patch of skin in which melanocytes show hyper-reactivity to uv stimulation. Get darker with sunlight

lentigo: sharply demarcated macule occupied by an increased number of melanocytes that do not respond to UV

Nevus: (mole) developmental abnormality of the skin characterized by accumilation of melanocytes

Question 39

Pigmented lesions: Nevus

Answer 39

• can be located in the dermis (dermal nevus, dermoepidermal junction (junctional nevus), or both junctional and dermal (compound nevus), or blue nevus - deep
• 2 groups: congential : birthmarks with no significnace
  aquired: appears at puberty and become more prominent in adult life, and then involute. Usually innoculus skin lesions and do not require treatment. Malignant potential is very low.

Dysplastic nevi may progress to malignant melanoma. Occur at high rate in cancer prone families, and if untreated progress to malignant in 50% of cases.

Question 40

Malignant Melanoma

Answer 40

• tumor originating from melanocytes. Most significant, nb to dx early
• 1/2 arise from intact skin, the other from freckles and nevi

3 types:

Lentigo melanoma: Flat, macular lesion that typically comes from pre-existig freckle, usually in elderly. It localizes for up to 10-15 years, and if not removed progresses to a superficial spreading or invasive nodular melanoma.

Superficial spreading melanoma accounts for 70% of all malignant pigmentory tumors, and is most common form of clinically recognized melanomas. Present as irregularly pigmented macules with irregular edges. Lesions are pruitic, most common on legs of women and backs of men. As the tumor progresses, it invades the epidermis, dermis, giving rise to nodular melanoma.

Nodular melanoma: Rapidly growing, infiltrating variant of malignant melanoma. Marked by vertical growth and invasion of dermis. Extent of dermal invasion is the most nb prognostic sign.

acral-lentiginous: develop of palms and plantar surfaces, or underneath nails. Most common in Afican and Asain Americans

Question 41

Clinical Features of melanoma

Answer 41

• r/t sun exposure. Races that have little skin pigment are more susscpetible.
• at least 1/3 to 1/2 originate from lentigines, or acquired or dysplastic nevi
• therefore NB to recognise transition.

DX. A, B, C, D

A: Asymmetry

B: Borders (irregular margins)

C: Color: variations

D; Diameter: most are 6mm or more, but can be smaller

Question 42

TX. of melanoma

Answer 42

• surgical
• chemo and rad for mets
• overall 5 year survival for all forms is 60%

Question 43

Dermal and Connective Tissue Tumors:

Answer 43

• Dermal tumors may originate from firboblasts, blood vessels, and many other structures
• most common is dermatofibroma- benign composed of fibroblasts. surgical is tx.
• Karposki’s sarcoma: dermal tumor composed of blood vessels and perivascular connecive tissue cells. Red tumors present as hemmorhagic nodules, which are multiple and confluent. Previously rare, but more common with AIDS (not known why). Low malignant potential, may metastasize in immunocompromised state. No adequate tx. available.

Question 44

Derman tumors from bloodborne cells

Answer 44

• Skin may be affected by malignant cells that may reach it through blood circulation
• common to see dermal infiltrates of malignant lymphoma or other visceral malignant lesions. T-Cell lymphoma has preselection for this skin - one is called mycosis fungoids. Which presents as skin macules and papules that progress to nodules and ulcerating large masses.

Uticaria pigmentosa: dermal infiltrates of mast cells. common in children and teens. Present with pigmented brown red macules that flare on toucing or stroking

Question 45

Diseases of the nail

Answer 45

• manifold- some reflect local conditions, some systemic disorders
• spoon shaped nail- iron deficiency. club- hypoxia
• nails are resistant to infection except base and cuticle
• Paronychia: bacterial infection. common with water -kitchen personel.
• onychomycoses: fungi - resistant to tx., typically chronic

Question 46

Hisutism

Answer 46

• excess hair. most instances cause is unknown
• female hirtuisim usually sign of hormonal imbalance. Adrogen producing overian or adrenal tumors, or complex hormonal distrubances by polycycstic ovary are well known causes of beard or chest hair in females. Upper lip hair not always possible to explain hormonally

Question 47

Alopecia

Answer 47

-loss of hair from scalp. May be focal (areata), diffuse, or universal.

Focal (areata): may be idiopathic, or autoimmune. Can be caused by fungi or bacteria. Nervous hair pulling also.

Diffuse Alopecia: large portions of scalp. occurs in again males. idiopathic but also hereditary. alopecia in women usually hormonal disorders (hypothyroid or nutrition)

alopecia universalis: cytotoxic. scalp, eyebrows, body hair