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Skin Disorders: Characteristics, Causes, and Types, Study notes of Pathophysiology

An in-depth analysis of various skin disorders, their characteristics, causes, and types. It covers topics such as skin lesions, inflammatory disorders, hives, eczema, psoriasis, skin infections, viral infections, warts, fungal infections, pediculosis, scabies, and skin tumors. The document also discusses warning signs of skin cancer and the importance of early detection.

Typology: Study notes

Pre 2010

Uploaded on 08/08/2009

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Skin Disorders
Bio 375
Pathophysiology
Skin Lesions
Characteristics of skin lesions are often
helpful in making a diagnosis
Skin lesions may be caused by:
Systemic disorders, e.g. liver disease
Systemic infections, e.g. chickenpox rash
Allergies to ingested food or drugs
Localized factors
Some common skin lesions follow:
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Skin Disorders

Bio 375

Pathophysiology

Skin Lesions

„ Characteristics of skin lesions are often

helpful in making a diagnosis

„ Skin lesions may be caused by:

„ Systemic disorders, e.g. liver disease „ Systemic infections, e.g. chickenpox rash „ Allergies to ingested food or drugs „ Localized factors

„ Some common skin lesions follow:

An open comedone has a dilated orifice (blackhead) and a closed comedone has a narrow opening (whitehead)

Important Characteristics of

Skin Lesions

„ Location of lesion „ Length of time the lesion has been present „ Any changes occurring over time „ Physical appearance including: „ Color „ Elevation „ Texture „ Type of exudate „ Presence of pain or itching „ Itching (pruritus) is associated with allergic responses, chemical irritation due to insect bites or infestations such as scabies (a mite)

„ Urticaria (Hives) „ Results from type I hypersensitivity (IgE mediated release of histamine) reaction caused by ingested substances: „ Shellfish „ Certain fruits like strawberries „ Drugs like penicillin or aspirin „ Systemic diseases like intestinal parasites „ Physical agents like heat or cold „ The release of histamine causes the eruption of hard, itchy, raised red wheals on the skin, often scattered all over the body „ Occasionally, hives develop in the pharyngeal mucosa and may obstruct the airway causing difficulty in breathing

Hives

„ Atopic dermatitis (Eczema) „ A common problem in infancy and may persist in adulthood in some persons „ In infants the itchy lesions are typically moist, red, vesicular and covered with crusts „ In adults the affected skin is dry and scaling with lichenification; itching is common „ Atopic refers to an inherited tendency toward allergic conditions „ Typically, the family history includes individuals with eczema, allergic rhinitis or hay fever and asthma „ A type I hypersensitivity (increased IgE levels)

Eczema is common

in infancy and

childhood

Skin Infections

„ Bacterial infections

„ Common type of skin infection „ May be primary (due to resident flora) „ May be secondary (developing in wounds or pruritic lesions) „ Some are superficial; others form deeper abscesses

Cellulitis (Erysipelas)

„ Cellulitis is an infection of the dermis and subcutaneous tissue, usually secondary to an injury, furuncle (boil) or ulcer „ Causative agent usually Staphylococcus aureus or occasionally beta-hemolytic streptococcus „ Frequently occurs in the lower trunk or legs and the area becomes red, swollen and painful.

Furuncles (Boils)

„ Furuncle is an infection, usually byS.

aureus, which begins in a hair follicle

and spreads into the surrounding

dermis

„ Common locations are face, neck and

back

„ Initially, is firm, red, painful nodule

„ Develops into a large, painful mass that

frequently drains large amounts of pus

„ Squeezing boils can result in the spread of infection by autoinoculation to other areas of the skin and to cellulitis

„ Compression of furuncles in the nasal area may lead to thrombi or infection that spreads to the brain if the infected material reaches the cavernous sinus in the facial bones

„ Carbuncles are a collection of furuncles that coalesce to form a large infected mass

Furuncles

Impetigo

„ Common infection in infants and children „ S. aureus may cause highly contagious infections in neonates „ In older children, infection results primarily fromS. aureus but may be caused by beta-hemolytic streptococci „ Easily spread by infected hands, eating utensils and towels

„ Recurrance may be triggered by infection such as the common cold, sun exposure or stress. „ Spontaneous healing usually occurs in 2- weeks „ The virus is spread by direct contact with the fluid from the lesion „ Viral particles may be present in saliva for several weeks following “healing” and can be spread to others „ A potential complication is spread of the virus to the eyes, causing keratitis

Herpes Zoster (Shingles)

„ Caused by varicella-zoster virus (VZV) in adults

„ It is seen after a primary infection of varicella or chicken pox, which usually occurs in childhood

„ Shingles usually affects one cranial nerve or one dermatome on one side of the body „ Pain, paresthesia and a vesicular rash develop unilaterally along a line. „ Lesions persist for several weeks and then clear

Verrucae (Warts)

„ Warts are caused by the human

papillomaviruses (HPVs)

„ Many types of these viruses associated

with a variety of diseases

„ Plantar warts are a common type

„ Frequently develop in children and young adults; are annoying but relatively harmless „ Occur on soles of feet „ Tend to persist even with treatment

Scabies (Mites)

„ Scabies is a common infestation with a small mite that lives in the upper surface of the skin. „ Mites passed from person to person „ Rash varies but typically itches „ Often patches of eczema and small pustules around wrists and in the finger webs „ In children under 18 months, pustules sometimes seen on the soles of the feet

Skin Tumors

„ Skin lesions due to sun exposure have been on the increase for some time „ Estimated that 1 in 7 people will develop skin cancer „ In recent years there has been an increased emphasis on more sun exposure „ Incidence higher in those who have experienced severe sunburns, those who spend a lot of time in the sun and light skinned people with little melanin

Keratoses

„ Keratoses are benign lesions that are associated with aging or skin damage „ Seborrheic keratoses result from proliferation of basal cells, leading to an oval elevation that may be smooth or rough and is often dark in color; usually found on face or trunk „ Actinic keratoses occur on skin exposed to UV radiation and commonly arise in fair skinned people; usually pigmented and scaly; may develop into squamous cell carcinoma

Warning Signs of Skin Cancer

„ A sore that does not heal

„ A change in shape, size, color or texture

of a lesion, especially an expanding,

irregular circumference or shape

„ New moles or odd-shaped lesions that

develop

„ A skin lesion that bleed repeatedly,

oozes fluid, or itches

Kaposi’s Sarcoma

„ Most commonly seen in immunosuppressed patients such as those with HIV and AIDS

„ Often itchy and painful