DERMATOLOGY

AnatomyAnatomy

FunctionsFunctions

Diagnosis of Diagnosis of

skinskin diseasedisease

SKIN COLOR VARIATIONSSKIN COLOR VARIATIONS

SKIN CHANGES WITH AGESKIN CHANGES WITH AGE

SKIN FUNCTIONSKIN FUNCTION

• to form a protective layer over the body • to keep moisture in the body (water retention)• to make vitamin D• to regulate body temperature• to excrete waste• to sense pain, itch, light touch, heat, cold, and

other sensations• for communication

SKIN HISTOLOGYSKIN HISTOLOGY

• The outer layer of skin is the epidermis

• The inner layer is called the dermis. It contains hair follicles, nerves (the body's sense of touch), sweat and oil glands and blood vessels.

• Below the dermis is the subcutaneous tissue consisting of fat cells dispersed in a connective tissue framework

ANATOMY

NORMAL SKIN NORMAL SKIN HISTOLOGYHISTOLOGY

Criteria for Cutaneous Criteria for Cutaneous DiagnosisDiagnosis

• Location

• Number of Lesions

• Type of lesion

• Pattern

• How widespread

• Complaints

SKIN LESIONSSKIN LESIONS

•PRIMARY

•SECONDARY

PRIMARY LESIONSPRIMARY LESIONS

• Primary – original lesions

• Identification of such lesions is the most important aspect of the dermatologic examination

• May continue to full development or be modified by regression

PRIMERYPRIMERY

• Macule

• Papule

• Plaque

• Nodule

• Pustule

• Vesicle

• Bulla

• Wheal (hive)

• Ulser

MACULEMACULE

A circumscribed, flat discoloration that may be brown,blue, red, or hypopigmented.No elevation or depression of skin.No elevation or depression of skin.

BrownBlueRedHypopigmented

Becker's nevus. This lesion contains no pigmentation.

Becker's nevus. A typical lesion with macular pigmentation and hair.

BROWN MACULE

PAPULEPAPULEAn elevated solid lesion up to 0.5cm in diameter; color varies; papules may become confluent and form plaques.

Flesh colored, yellow, or white

Red

Brown

Blue or violaceous

Granuloma annulare. The dorsal surfaces of the hands and feet and the extensor aspects of the arms and legs are the most common sites. Lesions are either papular or broad superficial plaques.

Kaposi's sarcoma.

PAPULE

PLAQUEA circumscribed, elevated, superficial, solid lesion more than 0.5cm in diameter, often formed by the confluence of papules

Secondary syphilis. This is the uncommon follicular secondary syphilis.

PLAQUE

NODULE

A circumscribed, elevated, solid lesion more than 0.5cm in diameter; a large nodule is referred to as a tumor

Metastatic carcinoma of the breast. Nodules appear vascular and resemble Kaposi's sarcoma.

NODULE

PUSTULEPUSTULE

A circumscribed collection of leukocytes and free fluid that varies in size

Staphylococcal folliculitis.

VESICLE

A circumscribed collectionof free fluid up to 0.5cm in diameter Herpes zoster

BULLA

A circumscribed collection of free fluid more than 0.5cm in diameter

Bullosis diabeticorum.

WHEAL (HIVE)A firm edematous plaque resulting from infiltration of the dermis with fluid; wheals are transient and may last only a few hours

Dermographism

ULCER

A focal loss of epidermis and dermis; ulcers heal with scarring

Primary syphilis

CYST• Closed cavity that contains liquid or semisolid

material

SECONDARY

• Scale

• Crust

• Atrophy

• Lichenification

• Erosion

• Excoriation

• Fissure

• Scar

ScalesScalesFine to stratifiedFine to stratified Scaling in sheets (desquamation)Scaling in sheets (desquamation)

Excess dead epidermal cells that are produced by abnormal keratinization and sheddingThe may be fine, as in pityriasis;The may be fine, as in pityriasis;white and silvery, as in psoriasis; white and silvery, as in psoriasis; or large and fish-like, as in ichthyosis.or large and fish-like, as in ichthyosis.

Dominant ichthyosis

vulgaris

CRUST

A collection of dried serum and cellular debris; a scab

Impetigo. A thick, honey-yellow adherent crust covers the entire eroded surface.

EROSION

A focal loss of epidermis;erosions do not penetrate below the dermoepidermal junction and therefore heal without scarring

Toxic epidermal necrolysis

(Nikolsky's sign)

FISSURE

A linear loss of epidermis and dermis with sharply defined, nearly vertical walls

Asteatotic eczema. Excessive washing produced this advanced case with cracking and fissures.

ATROPHY

A depression in the skin resulting from thinning of the epidermis or dermis

Lichen sclerosus et atrophicus. The epidermis is thin and atrophic

and gives the appearance of wrinkled tissue paper

when compressed.

SCARAn abnormal formation of connective tissue implying dermal damage; after injury or surgery scars are initially thick and pink but with time become white and atrophic

Keloids on the chest and extremities are raised witha flat surface. The base is wider than the top.

EXCORIATION

An erosion caused by scratching;

excoriations are often linear

COMEDONE

A plug of sebaceous and keratinous material lodged in the opening of a hair follicle; the follicular orifice may be dilated (blackhead) or narrowed (whitehead or closed comedone)

MILIA

A small, superficial keratin cyst with no visible opening

BURROW

A narrow, elevated, tortuous channel produced by a

parasite

LICHENIFICATION

An area of thickened epidermis induced by scratching; the skin lines are accentuated so that the surface looks like a washboard

TELANGIECTASIA

Dilated superficial blood vessels

PETECHIAE

A circumscribed deposit of blood less than 0.5cm in diameter

PURPURA

A circumscribed deposit of blood greater than 0.5cm in diameter

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