The document provides an overview of diseases of the skin, including: - The functions of healthy skin and its layers (epidermis, dermis, subcutaneous) - Common types of skin diseases like infections (bacterial, viral, fungal, parasitic), hypersensitivity/allergic reactions, benign and malignant tumors - Characteristics and symptoms of specific infectious skin diseases like impetigo, cellulitis, herpes, and scabies - Diagnostic tests for identifying skin conditions like culturing lesions and skin biopsies.

1. DISEASES OF THE SKIN:
 I. FUNCTIONS OF THE SKIN
 The skin or the integument is a vital organ
 A “protective wrap”
 Regulates body temperature
 Senses pain
 Keeps harmful substances & microorganisms from entering body
 Provides a shield from harmful effects of the sun
 Largest organ of the human body
 Indicatesmalfunctionwithinthe bodythroughcolorchanges
 Cyanosis (blue) is lack of O2-cardiovascular problem
 Jaundice (yellow) – indicates liver disease from accumulation of bilirubin in the blood
 Abnormal redness – due to polycythemia, carbon monoxide poisoning, & fever
 Pallor (whitening) may indicate anemia
 OUTERMOST layeristhe EPIDERMIS
 Consists of stratified or squamous epithelium
 Top layer of epidermis contains KERATIN – a tough, fibrous protein that protects skin
from harmful substances
 Bottom layer of epidermis contains MELANIN – dark pigment in skin that protects body
from harmful rays of the sun

2.  DERMIS – “True Skin” lies below the epidermis
 Composed of connective tissue
 Supports blood & lymph vessels, elastic fibers, nerves, hair follicle, sweat glands &
sebaceous (oil) glands
 SUBCUTANEOUS –lies under the dermis
 Connects the skin to underlying structures (i.e. muscle, fat)
 Contains adipose (fat cells) tissue – helps insulate body from cold & heat
CLASSIFICATIONS OF SKIN DISEASES
 Skin diseases are identified and classified according to characteristic lesions (size, shape,
color & location) and other S & Sx’s
 PRURITIS – itching
 EDEMA – swelling
 ERYTHEMA – redness
 Inflammation –usually accompany lesions and are helpful in making a diagnosis (DX)
VESICLES – small blister-like eruptionsorlargerfluid-filledlesionscalledbullae.
 PUSTULES – lesions that contain pus
 MACULAR – flat lesions
 PAPULAR – raised lesions
 ERYTHEMATOUS – reddened area due to inflammation &/or injury
 Nodules & tumors – hard to the touch
 Pruritis – itching, which accompanies many skin diseases, especially allergic & parasitic

3. INFECTIOUS SKIN DISEASES
BACTERIAL
 IMPETIGO – is acute, contagious & common in children
 Caused by streptococcal & staphylococcal organisms in the nose & passed to the skin
 Erythema, reddened area develops and oozing vesicles and pustules form
 Area ruptures & yellow crust covers lesion
 Face & Hands most frequently affected
 Fever & enlarged lymph nodes may present
 Wash with soap & H20, dry, keep open to air
 ERYSIPELAS – inflammatory skin infection caused by streptococci
 Commonly appears on face, arm or leg
 Infection begins where skin is broken
 Shiny, swollen, red rash initially develops, often with small blisters
 Red rash is hot & tender to touch
 Fever & chills present when infection severe
 Treatment with antibiotics (ABX) when severe
 CELLULITIS - spreadinginfectionof the skinmost often causedby streptococcus
 Most common on the legs and begins with skin damage
 Affected area is swollen, red, & tender
 Sx’s may include fever & chills
 Treatment (TX)– prompt TX prevents the spread of infection to the blood & vital organs

4.  VIRAL SKIN INFECTIONS
Most common viruses cause cold sores or fever blisters & warts
 HERPES SIMPLEX – causes cold sores & fever blisters
 VERUCCA VULGARIS – causes WARTS
 Keratinocytes proliferate making the surface rough
 Most common in children & young adults
 Affects mostly the hands (Fig. 18-7 p.402)
 Multiple & CONTAGIOUS – spread by scratching
 Reoccurs if virus remains in body, not serious
 May disappear spontaneously, not painful
 Should only be removed by an M.D.
PLANTAR WARTS – foundon the SOLES OF THE FOOT
 GROWS INWARD, unlike other warts on the body which grow outward
(elevated)
 Painful, due to pressure on the soles of the foot when walking or standing
 Difficult to remove permanently
 GENITAL (VENEREAL) WARTS – very serious & difficult to remove
 VIRAL SKIN INFECTIONS
FUNGAL
 DERMATOPHYTES (FUNGI) –live on the dead,top layerof the skin
 Symptoms may or may not appear
 Serious infections – itching, swelling, blisters & severe scales
 Minor infections – mild irritation & swelling

5. PARASITIC INFESTATIONS
 PUBIC LICE – infest pubic hair and generally spread by sexual contact.
 Lice does not spread other STD’s
 TX – RX Cream
 BODY LICE – most common among underprivileged, transient people.
 Lice CAN SPREAD DISEASE – such as typhus epidemics among soldiers during war
 Prevention – good grooming & hygiene
 SCABIES “THE ITCH” – causedby a parasiticMITE
 HIGHLY CONTAGIOUS
 Female mite – burrows into skin folds of groin, under breasts, between fingers &
toes. Lays eggs in tunnels of folds, eggs hatch, cycle begins again
 Spread via close contact & linked to other VD’s
 Blisters & pustules appear
 Itching – caused by hypersensitivity to mite & opens up skin to other bacterial
infections
 Epidemics common in camps & barracks (poor living)
 TX & Recovery – Hot baths & scrubbing & meds. Underwear & bedding changed
& washed frequently.

6.  V. HYPERSENSITIVITY OR IMMUNE DISEASES OF THE SKIN
 HYPERSENSITIVITY – ALLERGIC reactions of the skin. Emotional stress may trigger or
exacerbate an allergy-caused skin disease.
 INSECT BITES – Bites & stings can produce local inflammatory reactions.
 Acute reactions – hives
 Chronic reactions – papules (solid elevations)
 Bullous – blisters
 URTICARIA (HIVES) – VASCULARREACTION OFTHE SKIN TO AN ALLERGEN
 WHEALS – lesions round elevations with red edges & pale centers
 Extremely itchy
 Histamine released – cause blood vessels to dilate, followed by edema & intense
itching
 Common causes – food, allergens & stress
 TX- steroids, antihistamines, topical creams
 DRUG ERUPTIONS –Adverse drugreactionsmanifestmore oftenonthe skinthanany
otherorgan system.
 Topical drugs – mild pimples over sm. Area to peeling of the skin
 Serious reactions may lead to anaphylaxis shock or death.
 Most common offending drugs are penicillin, sulfa, morphine, codeine, etc.

7. VI. BENIGN TUMORS
 NEVUS (MOLE) – small, dark skin growth that develops from pigment-producing cells or
melanocytes.
 Appear flat or raised & vary in size
 Most people have about 10 moles
 Usually harmless, but can become malignant
 Sudden changes in moles such as enlargement, irregular border, darkening,
inflammation & bleeding are warning signs of malignancy
 SKIN CANCER
 BASAL CELL CARCINOMA – most common skin cancer. Slow growing, generally non-
metastasizing (spreading) tumor.
 Develops on face of light skinned people exposed to sun
 Lesions begin as a pearly nodule with rolled edges that may bleed and form a crust
 Ulceration occurs and size increases if neglected
 TX- surgical removal, cauterize, or radiation.
 KAPOSI’S SARCOMA– Purplishneoplasmof the lowerextremities.
 Lesions – red to purple lesions varying from macules (flat) to nodules (hard nodes)
 This skin cancer is epidemic in AIDS patients
 Cause of 11% of AIDS-related deaths
 MALIGNANTMELANOMA – the MOST SERIOUS skincancer. Arisesfromthe melanocytesof the
epidermis.
 HIGHLY MALIGNANT and metastasis is early
 Sometimes develops as a mole that changes in size, color & becomes itchy & sore.
 TX-surgical removal with the surrounding lymph nodes to reduce metastasis

8.  SEBACEOUS GLAND DISORDERS
 Hyperactivity of the sebaceous glands causes acne and chronic dandruff. Raised, horny
lesions result from an excessive production of keratinocytes.
 ACNE (VULGARIS) – blackheads, pimples and pustules.
 Affects many adolescents, about 80% between the ages of 12 – 15.
 Mild form – non-inflammatory acne with few white & black heads.
 Inflammatory acne – severe breakout of pus-filled pimples & cysts that cause deep
pitting & scarring
 DIAGNOSTIC TESTS FOR SKIN DISEASES
 Skin conditions are normally identified by its characteristics such as size, shape, color,
location & presence or absence of systemic S&SX’s
 Culturing the purulent lesion usually identifies the bacterial, fungal, and viral
infections.
 Culture grows & specimen is identified under a microscope
 Biopsies (tissue sample) are usual for neoplastic (abnormal new growth) lesions,
chronic eruptions, and nodular lesions
 Excised tissue is about 1/8 inch in diameter and is examined under a microscope.
SUBMITTED BY:
SADAF
SUBMITTED TO:
Dr ARSALAN