Transcript Diseases of the Skin

Human Diseases
A Systemic Approach
Sixth Edition
Mary Lou Mulvihill
Mark Zelman
Paul Holdaway
Elaine Tompary
Jill Raymond
Chapter 17
Diseases of the Skin
Mulvihill, Zelman, Holdaway, Tompary, and Raymond
Human Diseases: A Systemic Approach, 6e
Copyright ©2006 by Prentice-Hall, Inc.
Upper Saddle River, New Jersey 07458
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Chapter 17
Diseases of the Skin
Multimedia Asset Directory
Slide 53
Slide 64
Slide 78
Slide 96
Slide 98
Eczema
Skin Cancer
Acne
Decubitus Ulcer
Pressure Ulcer
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Functions of the Skin
 Protective wrap, regulates temperature, senses pain,
keeps substances and microorganisms from entering the
body, and provides a shield from the harmful effects of
the sun
 Indicates malfunction within the body through color
changes
– Cyanosis, a blue coloration of the skin in the extremities signals
a lack of oxygen, indicating a cardiovascular or pulmonary
problem.
– Jaundice indicates liver disease, bile obstruction, or hemolysis of
red blood cells.
– Abnormal redness accompanies polycythemia, carbon monoxide
poisoning, and fever.
– Pallor, or whitening of the skin, may indicate anemia.
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Figure 17-1: Structure of the skin.
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Structure of the Skin
Epidermis
 The outermost layer of the skin
– Consists of stratified or layered squamous epithelium.
– Stratum corneum contains keratin, a tough, fibrous
protein produced by cells called keratinocytes and
protects the skin from harmful substances.
– At the bottom of the epidermis are the melanocytes,
or the cells that produce melanin, the dark pigment of
the skin that protects the body from the harmful rays
of the sun.
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Structure of the Skin
Dermis and Subcutaneous Tissue
 The dermis or “true skin” lies below the
epidermis.
– Composed of connective tissue that supports blood
and lymph vessels, elastic fibers, nerves, hair
follicles, sweat glands, and sebaceous or oil glands.
 The subcutaneous tissue lies under the dermis
and connects the skin to underlying structures.
– Adipose tissue or fat cells are in the subcutaneous
tissue and help insulate the body from heat and cold.
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Skin Diseases
 Identified and classified according to
characteristic lesions
– Revealing characteristics of skin lesions
include the size, shape, color, and location as
well as the presence or absence of other
signs and symptoms.
– Pruritis (itching), edema (swelling), erythema
(redness), and inflammation usually
accompany lesions and are helpful in making
a diagnosis.
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Figure 17-2: Skin signs are objective evidence of an illness
or disorder. They can be seen, measured, or felt.
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Lesions
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Vesicles: Blisterlike eruptions
Bullae: Large fluid-containing lesions
Pustules: Lesions containing pus
Nodules: Also known as tumors, lesions that are hard to
the touch
Macular: flat lesions
Papular: raised lesions
Erythematous: An area of skin reddened by congested
blood vessels resulting from injury or inflammation
Pruritus: itching, accompanies many skin diseases
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Infectious Skin Diseases
 Bacteria, viruses, fungi, and parasites may
cause infections of the skin.
 Normal microbes that reside on the skin cause
the most common skin infections.
 Infections from less common microbes may
develop in high-risk individuals
(immunocompromised or diabetic individuals),
and those who reside in nursing homes and
hospitals.
 Most skin infections are not serious unless
systemic involvement occurs.
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Impetigo
 Acute, contagious skin infection common in children
 Caused by streptococci and staphylococci carried in the
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nose that is passed to the skin.
The face and hands are most frequently affected.
Erythema develops and oozing vesicles and pustules
form.
Fever and enlarged lymph nodes may accompany the
infection.
Treatment: The lesions should be washed with soap
and water, kept dry, and exposed to air. Antibiotic
ointment may be used, and oral antibiotics are
sometimes prescribed to treat the infection systemically.
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Erysipelas
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An inflammatory skin infection caused by Streptococci
Infections appear on the face, arm, or leg.
Infection may begin with broken skin.
A shiny, swollen, and red rash may develop initially and
is often accompanied by small blisters.
 The erythematous rash is hot to touch and tender.
 Fever and chills develop when the infection is severe.
Mild erysipelas is self-limiting; however, when the
infection is severe, treatment with antibiotics is required.
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Cellulitis
 A spreading infection of the skin that is most
often caused by Streptococci
 The infection is common on the legs and begins
with skin damage.
 The involved area is generally swollen, red, and
tender.
 Symptoms of the infection may include fever and
chills. Prompt treatment prevents the spread of
the infection to the blood and vital organs.
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Figure 17-3: Cellulitis indicated by redness and swelling
around the eye. (Courtesy of the CDC / Dr. Thomas F.
Sellers / Emory University, 1963)
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Folliculitis
 An inflammation of the hair follicles caused
by infection with Staphylococci
 A small number of pustules develop in the
hair follicle.
 Commonly occurs in young men and
affects thighs, buttocks, beard, and scalp
 Treatment: daily cleansing with an
antiseptic soap. Severe cases require
treatment with oral antibiotics.
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Figure 17-4: The lesions of folliculitis are pustules
surrounded by areas of erythema.
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Furuncles and Carbuncles
 Furuncles
– Boils; large, tender, swollen raised lesions caused by
Staphylococci.
– The infection appears in hair follicles located on the face, neck,
breasts, or buttocks. The core of the furuncle become necrotic
and liquefies, forming pus.
 Carbuncles
– Clusters of boils
– These lesions arise in a cluster of hair follicles. Carbuncles
develop and heal more slowly than boils.
– They appear mostly in men and are commonly located on the
back of the neck.
 Treatment: moist heat, antiseptic skin cleansing, topical
or oral antibiotics and incision and drainage
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Figure 17-5: A furuncle (or boil) is a deep, red, painful
nodule.
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Viral Skin Infections
Herpes
 Herpes is a large family of viruses that
cause clusters of fluid-filled vesicles on the
skin. The virus remains in the body for
life.
 Herpes Simplex Type I
 Herpes Simplex Type II
 Herpes Varicella-Zoster
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Herpes Simplex Type I and Type II
 Herpes simplex type I
– Causes cold sores or fever blisters
– The virus may be harbored in the body for a long time with no ill
effect, but suddenly it becomes active and the infection
develops.
– Triggers: low resistance to infection, stress, respiratory
infections, common cold, menstruation sunburn
 Treatment: antiviral drugs are used, and antibiotics are
sometimes applied topically to treat secondary bacterial
invasion.
 Herpes simplex type II
– Causes genital herpes
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Figure 17-6: Typical cold sores or fever blisters caused by
the virus herpes simplex.
(Courtesy of the CDC / Dr. Herrman, 1964.)
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Herpes Varicella-Zoster
 Causes chicken pox, one of the most common childhood
infectious diseases
 The virus can be transmitted by airborne particles or by
direct contact.
– A rash forms over the face, trunk, and extremities. The rash
spots develop into vesicles in a few days causing intense
pruritis. The vesicles break, dry, and become crusty. Treatment
is usually symptomatic.
 If an adult develops limited immunity to Herpes varicella-
zoster the virus may lie dormant for years after recovery
from chicken pox. The virus may flare up during periods
of stress, diseases, trauma, or immunosuppression
causing painful vesicles called shingles.
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Warts
 Verucca vulgaris are caused by viruses affecting the
keratinocytes of the skin, causing them to proliferate.
 A benign neoplasm develops with a rough keratinized
surface.
 Most common in children and young adults, developing
particularly on the hands. They are often multiple and
are contagious, being spread by scratching.
– Warts sometimes disappear spontaneously, but only a physician
via surgery, cryosurgery, or laser can remove them. If the virus
remains in the body, the warts tend to recur.
 Plantar warts form on the soles of the feet
– Grow inward
– Pressure on the soles of the feet makes them very painful, and
they are often difficult to remove permanently.
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Figure 17-7: The common wart is a lesion of the skin caused by a virus.
It commonly appears as a raised, dome-shaped lesion.
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Fungal Skin Infections
 Fungi, or dermatophytes, that infect the
skin tend to live on the dead, top layer of
the skin. Fungal infections may or may not
cause symptoms. Minor infections cause
mild irritation and swelling. Serious
infections generally cause itching,
swelling, blisters, and severe scales.
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Tinea
 Tinea, or ringworm, is caused by many different fungi.
 Classified by its location on the body
 Fungi particularly reside in warm moist areas of the
body, but may also occur with hairy skin on the head,
groin, arms, and legs.
 Symptoms range from mild scales or cracking skin, to
painful raw rashes.
 Treatment includes keeping the affected area clean and
dry, and application of topical antifungal creams,
powders, and solutions.
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Tinea Corporis and Tinea Pedis
 Body ringworm affects smooth areas of skin on
the arms, legs, and body.
 Characterized by a pink to reddish rash that
sometimes forms round patches with clear areas
in the center
 Scales and fissures on the soles of the feet and
between the toes characterize tinea pedis or
athlete’s foot
 A foul odor usually accompanies the lesions.
 Tinea pedis is highly contagious and is spread
by direct contact with contaminated surfaces.
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Tinea Cruris
 Jock itch generally affects the groin and
upper and inner thighs.
 The fungi cause red, ring-like areas with
blisters
 Tinea cruris develops more frequently
during warm weather.
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Tinea Capitis
 Scalp ringworm is highly contagious and
most commonly occurs in children.
 This fungus may produce a mild scaly rash
or a patch of hair loss without a rash.
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Tinea Unguium
 Nail fungus affects nails, typically toenails.
 This fungus is difficult to treat because it hides
under the nail.
 The infection begins at the nail tips causing
white patches, eventually turning the nail brown.
The nail thickens and cracks.
 If left untreated the fungus may destroy the
entire nail, and tends to spread to other nails.
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Tinea Barbae
 Causes barber’s itch
 The fungus affects bearded areas of the
face and neck.
 This fungus may produce deep,
inflammatory pustules and crusting around
hairs.
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Table 17-1: Ringworm or Tinea Classification and
Symptoms
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Figure 17-8: Tinea corporis or body ringworm.
(Courtesy of the CDC / Lucille K. Georg, 1964.)
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Figure 17-9: Tinea pedia or athlete’s foot.
(Courtesy of the CDC / Lucille K. Georg, 1964.)
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Figure 17-10: Tinea cruris or jock itch.
(© Custom Medical Stock Photo)
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Figure 17-11: Tinea capitis or scalp ringworm.
(Courtesy of the CDC, 1959.)
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Figure 17-12: Tinea unguium or nail fungus.
(Courtesy of the CDC / Dr. Edwin P. Ewing, Jr., 1997.)
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Figure 17-13: Tinea barbae or barber’s itch.
(Courtesy of the CDC, 1975.)
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Candidiasis
 Infection appears on the skin, mucous membranes,
or fingernail.
 Candidiasis on the skin
– May produce patches of itchy red blisters and pustules,
the nail may turn white or yellow in color and separate
from the finger or toe
 Vaginal candida infections are common in pregnant
women, diabetics, or those who are
immunocompromised.
– Vaginal candidiasis is commonly known as a “yeast
infection” and frequently occurs after antibiotic therapy.
– Symptoms include a white “cottage cheese” -like discharge from the
vagina accompanied by burning, itching, and redness. Vaginal
candidiasis is effectively treated with vaginal antifungal creams, or oral
antifungal agents.
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Candidiasis (continued)
 Thrush or Candida infection of the mouth:
– Creamy white patches on the tongue or side of the
mouth often characterize a Candida infection of the
mouth or thrush.
– The patches are often painful and can easily be
scraped off. Thrush is common in young healthy
children, immunosuppressed adults, and diabetics.
– Long-term treatment of oral thrush with topical liquids
or oral antifungals is generally required.
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Figure 17-14: Candidia albicans, a fungus, causes a skin infection
characterized by erythema, pustules, and a typical white substance
covering the area.
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Parasitic Infestations
 Pediculosis
 Scabies
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Pediculosis
 Head lice
– Lice are spread from head to head directly or
indirectly by shared combs, scarves, hats, and bed
linen.
– Symptoms: itching, scratching that follows can open
the skin to other invading organisms.
– Adult head lice are difficult to see, but their white
eggs, called nits, can be located on the hair shaft.
– Treatment includes use of medicated shampoos
followed by use of a fine-toothed comb. Over-thecounter medications are also available.
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Pediculosis (continued)
 Pubic lice
– Infest pubic hair of both men and women and are
generally spread by sexual contact. Treatment
includes use of a prescription cream
 Body lice
– Most common among underprivileged, transient
people, this type of infestation can be prevented with
good grooming and hygiene.
– Body lice can spread serious disease, and they have
been responsible for typhus epidemics among
soldiers during wartime.
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Scabies
 Caused by a parasite called a mite
– The female mite burrows into skin folds in the groin, under the
–
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–
–
breasts, and between fingers and toes. As she burrows, she lays
eggs in the tunnels, the eggs hatch, and the cycle starts again.
Symptoms: intense itching, blisters, and pustules develop, and
the tunnels in the skin appear as grayish lines.
Scratching opens the lesions to secondary bacterial infection.
Scabies is transmitted by close personal contact and can be
linked to a venereal disease.
Epidemics of scabies are common in camps and barracks.
 Treatment: mites and eggs must be totally destroyed by
hot baths, scrubbing, and medications to eliminate them.
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Figure 17-15: Photodermatitis
(Courtesy of Jason L. Smith, MD.)
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Figure 17-16: Exfoliative dermatitis is an inflammatory skin
disorder causing excessive skin peeling.
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Hypersensitivity of Immune
Disorders of the Skin
 Insect bites
 Urticaria
 Eczema
 Poison ivy
 Drug-related eruptions
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Insect Bites
 Insect bites and stings can produce local
inflammatory reactions that may vary in
appearance.
 Acute reactions may appear as hives
whereas more chronic reactions may
appear as papules or bullae.
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Urticaria (Hives)
 Results from a vascular reaction of the skin to an
allergen
 The lesions are wheals, rounded elevations with
red edges and pale centers.
 Allergic response
– mast cells, release histamine, dilation and
permeability of blood vessels, infiltration of blood
proteins and fluid into the tissues = edema.
 Treatment: steroids, antihistamines, and
calamine lotion; elimination of allergen or irritant
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Eczema
 Contact dermatitis is a noncontagious
inflammatory skin disorder.
 Results from sensitization that develops from
skin contact with various agents, plants,
chemicals, and metals
 A delayed type of allergic response in which
lymphocytes are sensitized by an antigen, and
react with it on subsequent exposure
– The typical inflammatory reaction occurs: dilated
blood vessels, reddened skin, and edema, vesicles
and bullae develop from the excess tissue fluid, and
the lesions are very itchy.
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Eczema (continued)
 Contact dermatitis can affect anyone
– Skin that has been damaged is more easily
sensitized
 Corticosteroids are sometimes used to reduce
the inflammatory reaction.
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eczema.
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Poison Ivy
 Contact with poison ivy can cause an extremely
itchy rash with blisters and hive-like swelling.
– The response is a typical example of allergic contact
dermatitis.
 Severity of the condition depends on the amount
of plant resin on the skin and the individual’s
sensitivity to it.
– Initial exposure to the poison ivy plant produces no
visible effect but sensitizes the person to subsequent
exposure.
– The rash usually develops a few hours or a few days
after contact. Treatment to lessen the inflammation is
use of a topical cortisone-type cream, gel, or spray.
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