MORPHOLOGYPrimary Lesions

Secondary LesionsSpecial Lesions

Primary Lesions

Macule• Flat discoloration (any color) up to 1 cm

Patch• Flat discoloration (any color) greater than

1 cm

Papule• Palpable lesion up to 1 cm• May become confluent to form plaque

Plaque• Palpable lesion greater than 1 cm

Nodule• Circumscribed, elevated, solid lesion

greater than 1 cm

Tumor• A very large nodule

Vesicle• Circumscribed collection of free fluid up to

1 cm

Pustule• Circumscribed collection of pus up to 1

cm

Bullae• Circumscribed collection of free fluid

greater than 1 cm

Wheal (hive)• Firm, edematous

plaque resulting from infiltration of the dermis with fluids

• Transient; may last only a few hours

Secondary Lesions

Scales• Excess dead epidermal cells that are

produced by an abnormal keratinization and shedding

Crust• Collection of dried serum and cellular

debris (a scab)

Erosion• Focal loss of

epidermis• Does not pass the

dermoepidermal junction

• Heals without scarring

Ulcer• Focal loss of epidermis and dermis• Heals with scarring

Fissure• Linear loss of

epidermis and dermis with sharply defined nearly vertical walls

Atrophy• Depression in the skin

resulting from thinning of the epidermis or dermis

Scar• 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

Special skin lesions

Comedone• Plug of sebaceous

and keratinous material lodged in the opening of a hail follicle

• Closed comedone = white head

• Open comedone = black head

Excoriation• An erosion caused by scratching; often

linear

Lichenification• Area of thickened

epidermis induced by scratching

• Skin lines are accentuated so that the surface looks like tree-barking

Petechiae• Circumscribed tiny deposit of blood (up to

0.5 cm)

Purpura• Circumscribed deposit of blood greater

than 0.5 cm

Ecchymoses• Very large purpuric lesions

Name that lesion!Use the proper terminology to

describe the predominant lesion (primary, secondary or special) shown in the following photos.

Macules

Papules

Pustules

Nodule

Patch

Tumor

Vesicles

Vesicles

Scales

Crust

Patches

Erosion

Fissures

Atrophy

Lichenification

Comedones

Erosion & Crust

Bullae

Papules

Fissures

Plaques

Lichenification