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InfoLink: Clinical Advisor

SKIN IQ: Primary and Secondary Lesions

Section Editor(s): Hess, Cathy Thomas BSN, RN, CWOCN, Department Editor

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Identifying Primary and Secondary Skin Lesions

Primary skin lesions are present at the onset of a disease. In contrast, secondary skin lesions result from changes over time caused by disease progression, manipulation (scratching, picking, rubbing), or treatment. These 2 types of skin lesions can be differentiated as follows:

Primary lesions

  • Bulla—a vesicle (see definition below) greater than 5 mm in diameter
  • Cyst—an elevated, circumscribed area of the skin filled with liquid or semisolid fluid
  • Macule—a flat, circumscribed area; can be brown, red, white, or tan
  • Nodule—an elevated, firm, circumscribed, and palpable area greater than 5 mm in diameter; can involve all skin layers
  • Papule—an elevated, palpable, firm, circumscribed area generally less than 5 mm in diameter
  • Plaque—an elevated, flat-topped, firm, rough, superficial papule greater than 2 cm in diameter; papules can coalesce to form plaques
  • Pustule—an elevated, superficial area that is similar to a vesicle but filled with pus
  • Vesicle—an elevated, circumscribed, superficial, fluid-filled blister less than 5 mm in diameter
  • Wheal—an elevated, irregularly shaped area of cutaneous edema; wheals are solid, transient, and changeable, with a variable diameter; can be red, pale pink, or white.

Secondary lesions

  • Crust—a slightly elevated area of variable size; consists of dried serum, blood, or purulent exudate
  • Excoriation—linear scratches that may or may not be denuded
  • Lichenification—rough, thickened epidermis; accentuated skin markings caused by rubbing or scratching (eg, chronic eczema and lichen simplex)
  • Scale—heaped-up keratinized cells; flakey exfoliation; irregular; thick or thin; dry or oily; variable size; can be white or tan.


Hess CT. Clinical Guide: Wound Care. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
    © 2005 Lippincott Williams & Wilkins, Inc.