Introduction to Dermatology

Macule

Small flat spot, up to 1.0 cm

Patch

Flat spot, 1.0 cm or larger

Papule

Solid elevation up to 0.5 cm

Wheal

somewhat irregular, relatively transient, superficial area of localized skin edema

Plaque

elevated superficial lesion > 2 cm (often formed by coalescence of papules

Nodule

Marble-like lesion larger than 0.5 cm, often deeper and firmer than a papule

Cyst

Nodule filled with expressible material (either liquid or semisolid)

Vesicle

Up to 0.5 cm, filled with serous fluid

Bulla

> 0.5 cm, filled with serous fluid

Pustule

Papule filled with pus

Scales

a thin flake of dead exfoliated epidermis

Crust

The dry residue of skin exudates such as serum, pus, or blood (Scab)

Lichenification

Visible and palpable thickening of the epidermis and roughening of the skin (+/- scales)

Scar

Connective tissue that arises from injury or disease

Keloid

hypertrophic scarring that extends beyond the borders of the initiating injury

Erosion

Non-scarring loss of the superficial epidermis : surface is most but will not bleed

Excoriation

Linear or punctate erosions caused by scratching

Fissure

A liner crack in the skin, often resulting from excessive dryness

What is an example of erosion?

Aphthous stomatitis . moist area after rupture of vesicle

What is an example of excoriation?

cat scratches

What is an example of fissure?

Athlete's foot

Ulcer

a deeper loss of epidermis and dermis, may bleed and scar

What is an example of an ulcer

Decubitus ulcer (bed sore)

Petechiae & Purpura

A circumscribed deposit of blood, deep red or reddish purple (Petechia =1 to 3mm, Purpura > 3mm

Telangiectasia

Dilated superficial blood vessel

What is an example of Telangiectasia?

Rosacea

Ecchymosis

purple or purplish blue, faded to green, yellow and brown with time. Larger than petechiae

Comedone

Plug of sebaceous material in follicle

Closed Comedone

White head

Open Comedone

Blackhead

Ointments

Generally enhance the transport of active ingredient through the skin

Creams

More appealable to most patients

Lotions and gels

More desirable for conditions like acne