13.3, 13.4 Primary & Secondary Skin Lesions

Macule

• only color change

• <1 cm

Macule examples

freckles, flat nevi, hypopigementation, petechiae, measles, scarlet fever

Papule

• elevated

• <1 cm

• caused by superficial thickening in epidermis

Papule examples

elevated nevus (mole), lichen planus, molluscum, wart (verruca)

Patch

macules >1cm

Plaque

papules coalesce/combine >1 cm

Nodule

• solid, elevated, hard

• usually up to 2 cm

• may extend deeper into dermis

Wheal

• superficial, raised, transient, erythematous

• slightly irregular shape from edema

Tumor

• firm or soft, deeper into dermis

• benign or malignant

Urticaria (Hives)

wheals coalesce/combine, intensively pruritic (itchy)

Vesicle

• eleavted cavity of free fluid

• up to 1cm

• “blister”

Bulla

• >1cm

• usually single chambered

• easily ruptures

• friction blister

Cyst

• encapsulated fluid-filled cavity in dermis or subcutaneous

• wen, sebaceous cyst

Pustule

• pus in cavity (turbid fluid), circumscribed & elevated

• acne

What causes secondary lesions?

an evolutionary change in a primary lesion

Crust

vesicles or pustules rupture → thickened, dried out exudate

Scale

flakes of skin from dead excess keratin cells

Fissure

linear crack with abrupt edges (cheilosis/corners of mouth, athletes foot)

Erosion

scoped out, shallow depression & stays superficial (heals without scar)

Ulcer

deep deppression into dermis, heals with scar tissue

Excoriation

self-inflicted abrasion from intense scratching, superficial

Scar

after repair of skin lesion, normal tissue is lost and replaced with connective tissue (collagen), permanent fibrotic change

Atrophic Scar

• skin level is depressed with loss of tissue, thin epidermis

• striae

Lichenification

prolonged, intense scratching → thickens skin, lightly packed set of papules (look like surface of moss)

Keloid

benign excess scar tissue, feels smooth & firm