Pathophysiology - Skin Disorders

Question 1

Characteristics of epidermis

Answer 1

No blood vessels or nerves.
Five layers:
Stratum Basale (next to basement membrane) - only layer where mitosis occurs
Stratum Spinosum
Stratum Granulosum - keratin deposits
Stratum Lucidum (primarily in thick skin)
Stratum Corneum - dead, flat, keratinized cells
Big Strong Girls Love Cardio

Question 2

Keratin

Answer 2

A protein found in skin, hair and nails

Prevents both loss of body fluid through the skin and entry of excessive water

Question 3

Albinism

Answer 3

Recessive trait

Lack of melanin production

Question 4

Dermis

Answer 4

A thick layer of connective tissue that includes elastic and collagen fibers and varies in thickness over the body
Supports nerves and blood vessels
Sensory receptors for pressure, texture, pain, heat and cold

Question 5

Papillae

Answer 5

The junction of the dermis with the epidermis - irregular projections of dermis into the epidermal region. More capillaries located here to facilitate blood flow into epidermis

Question 6

Sebaceous glands

Answer 6

May be associated with hair follicles, may open directly onto skin. Produce sebum

Question 7

Sebum

Answer 7

Keeps hair and skin soft, retards fluid loss

Question 8

Sweat glands

Answer 8

Two types:
Eccrine, or merocrine, located all over the body, secrete sweat through pores onto the skin in response to increased heat or emotional stress
Apocrine - located in the axillae, scalp, face and external genitalia, ducts open onto hair follicles

Question 9

Subcutaneous Layer

Answer 9

Below dermis and epidermis, consists of connective tissue, fat cells, macrophages, fibroblasts, blood vessels, nerves and the base of many of the appendages

Question 10

Function of the skin

Answer 10

First line of defence against invasion by microorganisms, sebum is acidic and retards bacterial growth
Prevents excess fluid loss
Controls body temp - cutaneous vasodilation, secretion and evaportation of sweat
Sensory perception
Synthesis and activation of Vit D

Question 11

Macule

Answer 11

Small, flat, different colour

Question 12

Papule

Answer 12

Small, firm, elevated

Question 13

Nodule

Answer 13

Palpable elevated lesion, varies in size

Question 14

Pustule

Answer 14

Elevated, usually containing purulent exudate

Question 15

Vesicle

Answer 15

Elevated, thin-walled lesion, clear fluid (blister)

Question 16

Plaque

Answer 16

Large, slightly elevated lesion, flat surface, topped by scale

Question 17

Crust

Answer 17

Dry, rough surface or dried exudate or blood

Question 18

Lichenification

Answer 18

Thick, dry, rough surface (leather-like)

Question 19

Keloid

Answer 19

Raised, irregular, and increasing mass of collagen, result of excessive scar tissue formation

Question 20

Fissure

Answer 20

Small, deep, linear crack or tear in skin

Question 21

Ulcer

Answer 21

Cavity with loss of tissue from epidermis and dermis, often weeping or bleeding

Question 22

Erosion

Answer 22

Shallow, moist cavity

Question 23

Comedone

Answer 23

Mass of sebum, keratin and debris blocking opening of hair follicle

Question 24

How can scratching cause a secondary infection?

Answer 24

Increases inflammation, breaking the skin barrier, allowing microbes on fingers or surrounding skin to invade the area.

Question 25

Contact dermatitis

Answer 25

Caused by exposure to an allergen or by direct chemical or mechanical irritation of the skin. Ex metals, cosmetics, soaps, chemicals, plants.

Question 26

Urticaria

Answer 26

Hives
Commonly caused by ingested substances such as shellfish or certain fruits or drugs, the release of histamine causes the eruption of hard, raised lesions, highly pruritic.
Occasionally lesions may develop in pharyngeal mucosa and obstruct airway.

Question 27

Atopic dermatitis

Answer 27

Eczema
Atopic - inherited tendency toward allergic conditions
Results from the response to allergens
Eosinophilia and increased serum IgE levels indicate the allergenic basis
In children - Pruritic, moist, red, vesicular, covered with crusts
In adults - dry and scaling with lichenification, pruritis arms, legs, hands, feet.
Usually symmetrical on face, neck, arms, legs, buttocks

Question 28

First aid for Atopic Dermatitis

Answer 28

Elimination of aggravating agents
Topical glucocorticoids
Antihistamines may reduce pruritus
Avoidance of skin irritants like detergents or wool
Change to hypoallergenic diet
Moisturizing

Question 29

Psoriasis

Answer 29

Chronic inflammatory skin disorder, genetic, remissions and exacerbations.
Abnormal activation of T cells, associated increase in cytokines, leading to excessive proliferation of keratinocytes, rate of cell proliferation increased, increase in epidermal shedding. Lesions on face, scalp, elbows and knees.

Question 30

Treatment for psoriasis

Answer 30

Glucocorticoids, tar preparations, in severe cases the antimetabolite methotrexate, exposure to ultraviolet light.

Question 31

Pemphigus

Answer 31

Autoimmune disorder, several forms
Autoantibodies disrupt the cohesion between the epidermal cells causing blisters, the epidermis separates above the basal layer. Blisters form in the oral mucosa or scalp and then spread over face and trunk. The vesicles become large and rupture leaving large denuded areas of skin covered in crusts.
Treatment - systemic glucocorticoids such as prednisone and other immunosuppresants

Question 32

Scleroderma

Answer 32

Occur as skin disorder or may be systemic.
Increased collagen deposition, deposition in arterioles and capillaries reduces blood flow to skin and internal organs.
Inflammation, fibrosis, lead to hard, shiny, tight, immovable areas of skin. Atrophy in fingers, facial expression lost as skin tightens, movement of mouth and eyes impaired.
Can cause renal failure, intestinal obstruction, respiratory failure.

Question 33

Cellulitis

Answer 33

Infection of dermis and subcutaneous tissue, usually arising secondary to an injury, a furnuncle (boil) or an ulcer.
Causative organism is usually Staphylococcus aureus or Streptococcus.
Usually lower trunk and legs, particularly in those with restricted circulation or immunocompromised.
Red, swollen, painful, red streaks running along the lymph proximal to infected area.

Question 34

Furuncles

Answer 34

Infection, usually by S. aureus, beginning in a hair follicle, spreads into the surrounding dermis. Usually face, neck and back. Starts as firm, red, painful nodule, develops into abscess, drains lare amounts of purulent exudate.

Question 35

Autoinoculation

Answer 35

Spread of infection of microbes from one site of infection on the body to another
Can cause cellulitis

Question 36

Carbuncles

Answer 36

A collection of furuncles that coalesce to form a large infected mass

Question 37

Impetigo

Answer 37

Common infection in children. Staphylococcus aureus or A beta-hemolytic streptococci. Easily spread by direct contact with the hands, eating utensils, towels.
Lesions commonly occur on the face, begin as smal vesicles, rapidly enlarge and rupture to folm yellowish-brown crusty masses. Under crust, lesion exudes honey-colored liquid. Additional vesicles spread through autoinoculation. Pruritus also spreads infection.

Question 38

Treatment of impetigo

Answer 38

Topical antibiotics, possible systemic administration of antibiotics.

Question 39

Acute necrotizing fascilitis

Answer 39

Flesh-eating disease
Rapid tissue invasion, result of reduced blookd supploy to tissues and secretion of protease enzymes that destroy tissue.
Severe inflammation
Tissue necrosis primarily result from Streptococcus.
Often history of minor trauma or infection in the skin and subcutaneous layer, the fascia and soft tissues become edematous and necrotic, with occlusion of small blood vessels leading to gangrene.
Systemic toxicity develops with fever, tachycardia, hypotension, mental confusion, and disorientation, possible organ failure.

Question 40

Leprosy

Answer 40

Caused by bacterium Mycobacterium leprae
Generally affect skin, mucous membranes and peripheral nerves.
Skin lesions or macules, loss of feeling due to nerve damage
Person may damage or destroy tissue through injury but not know it immediately.

Question 41

Herpes Simplex

Answer 41

HSV-1 is most common cause of cold sores which occur on or near the lips.
HSV-2 may cause oral and genital lesions. Latent in the trigeminal nerve. Can be triggered by cold, sun, stress.
Spread by direct contact with fluid from the lesion.
Potential complication - can spread to eyes causing keratitis (infection and ulceration of the cornea)
Herpetic whitlow= - painful infection of the fingers

Question 42

Verracae

Answer 42

Warts
Caused by HPVs. Many types of these viruses, associated with a variety of diseases.
Common plantar warts are caused by HPV types 1-4.
Infection spreads by viral shedding of the surface skin.

Question 43

Fungal infections

Answer 43

Most are superficial because the funi live off the dead, keratinized cells of the epidermis.

Question 44

Tinea

Answer 44

Ringworm
Superficial
Tinea capitis - infection of the scalp common in children - circular bald partch as hair is broken off above scalp. Erythema or scaling
Tinea corporis - fungal infection of the body, particularly the nonhairy parts. Round erythematous ring of vesicles or papules with a clear center scattered over body. Pruritis, burning.
Tinea pedis, athlete’s foot.
Tinea unguium - infection of the toenails, turns the nail white and then brown.

Question 45

Scabies

Answer 45

Caused by a mite that burrows into the epidermis laying eyes. Larvae migrate to skin surface and then burrow into the skin to search for nutrients. Burrows appear as light brown lines, often with small vesicles and erythema. Inflammations and pruritis.
Fingers, wrists, inner surface of elbow, waistline.

Question 46

Pediculosis

Answer 46

Lice
Body louse, pubic louse, head louse.
Small, brownish parasites that feed off human blood.
Lay eggs on hair shafts, cementing the egg firmly to the hair close to the scalp. The egg appears as a small, whitish shell attached to a hair. Louse bites the host sucking blood. Site of each bite is a macule or papule, highly pruritic.

Question 47

Keratoses

Answer 47

Benign skin lesions, usually associated with aging or skin damage.
Seborrheic kertoses results from proliferation of basal cells, leading to an oval elevation that may be smooth or rough, often dark in color. Face and upper trunk.
Acinic keratoses - occur on skin exposed to ultraviolet radiation, commonly arise in fair skinned persons. Appears as pigmented, scaly patch. May develop into squamous cell carcinoma.

Question 48

Squamous cell carcinoma

Answer 48

Malignant tumor of epidermis, sun exposure major contributor, good prognosis. The invasive type - scaly, slightly elevated, reddish lesion, irregular border.

Question 49

Malignant Melanoma

Answer 49

Develops from melanocytes
Genetic factors, exposure to UV and hormonal influences.
Arise from melanocytes in basal layer of the epidermis or from a nevus (mole). Nevi that grow, change shape, color, size or texture or bleed are suspected.
Appears as multicolored lesion with an irregular border. Grows quickly, extends down into the tissues, metastasizes quickly to the regional lymph nodes then other organs.

Question 50

Kaposi’s Sarcoma

Answer 50

Associated with HIV
May affect viscera as well as skin. Malignant cells arise from endothelium in small blood vessels. Multiple skin lesions commence as purplish macules, often on face, scalp oral mucosa, lower extremities. Progress to form large, irregularly shaped plaques or nodules. May spread over upper body.

Question 51

What are some naturally occurring breaks in the human skin that allow bacteria to enter the body and cause infection?

Answer 51

The hair shaft and the sheathing follicle protrude from the skin, allowing bacteria to travel down the follicle and into the base, in the dermis. The sweat and sebaceous glands also have openings on the surface of the skin through which bacteria may travel down to the dermis and cause infection.

Question 52

How are precancerous lesions treated?

Answer 52

Surgery, laser therapy, electrodessication, cryosurgery

Question 53

Skin lesions are often itchy and uncomfortable. Why is this and how can this manifestation be treated?

Answer 53

Bacterial infections and reactions caused by allergens may spur the release of histamines, which can cause inflammation and pruritus, or itching, by stimulating the many sensory nerve endings in the skin. Antihistamines and glucocorticoids may be prescribed to relieve itching, and further pruritus may be prevented with the use of topical antiallergen creams and ointments.

Question 54

How can the skin disorder scleroderma also be responsible for renal failure?

Answer 54

Scleroderma involves the deposition of collagen, which causes tissue to be less elastic and more rigid, affecting capillary networks. Collagen deposition in the capillaries serving organs can cause obstructions that result in serious damage to organ tissue

Question 55

Why might a person with cellulitis see red streaks forming near the affected area?

Answer 55

The microorganism in question, usually S. aureus, can cause infection at one site and then travel by way of the lymph vessels, resulting in spread of the infection from the initial infection site.

Question 56

Why is a melanoma considered more dangerous than a squamous cell carcinoma when both are forms of skin cancer?

Answer 56

A melanoma may arise from a normal, benign mole and may not be readily recognized as a cancer. A melanoma may also originate in the deeper basal layer of the epidermis, again making it harder to detect one in its early stages. Melanomas grow rapidly and metastasize. A tumor’s appearance may change as it grows.