Annular: Arranged in a ring shape

Atrophy: Depressed surface due to thinned epidermis or dermis

Bulla: Blister > 1 cm

Burrow (papule): Linear ‘S’-shaped papule 3-5mm, found in scabies

Comedone (=papule): Plugged (pilo) sebaceous follicle: 1. Closed or whitehead 2. Open or blackhead

Crust (scab): Dried serum, pus or blood

Cyst (papule/nodule): Epithelium-lined cavity containing fluid, pus or keratin

Ecchymosis (bruise): Large confluent area of purpura

Erosion: Partial loss of epidermis. Heals without scarring

Erythema: Redness that blanches on pressure

Excoriation: Local damage due to scratching

Exudate: Serum, blood or pus accumulated on skin surface

Fissure: Linear split in epidermis or dermis

Keratin/Horn: Rough, uneven surface. Difficult to pick off, unlike crust

Lichenified: Thickened epidermis (and increased skin markings) due to excess scratching

Macule: Flat, pigmented lesion < 1 cm

Nodule: Raised lesion > 1cm with rounded surface *usually dermal pathology (no surface)

Papule: Raised lesion < 1cm

Patch: Flat, pigmented lesion > 1 cm

Petechia: Small, nonblanching, red-brown macules

Plaque: Raised lesion > 1cm (diameter>thickness) *usually epidermal pathology (surface e.g., scaling, crust, etc.)

Purpura: Red or purple skin that doesn’t fade with pressure

Pustule: Pus-filled lesion < 1cm

Scar (cicatrix) (macule/papule/plaque): Healed dermal lesion 2° to trauma, surgery, etc.

Serpiginous: Snake-like in appearance

Telangiectasia: Small dilated blood vessels

Ulcer: Full-thickness loss of epidermis & some dermis. Exudates or crusting present. Heals with scarring

Umbilicated: Round depression in centre of surface

Urticarial: Transient swelling due to dermal edema

Vesicle: Blister < 1cm

Warty/papillomatous: Finger-like/round projections on a surface