Version July 2025
| Morphology | Definition |
| Macule | Small (<1 cm) area of color change; no elevation and nonpalpable. |
| Patch | Large (>1 cm) area of color change; no elevation and nonpalpable. |
| Papule | Small (<1 cm) palpable lesion. |
| Nodule | Large (>1 cm) palpable lesion; usually dome shaped; margins may be distinct (sharp) or slope shouldered. |
| Plaque | Large (>1 cm) flat-topped and palpable lesion. |
| Vesicle | Small (<1 cm) fluid-filled blister; clear fluid. |
| Bulla | Large (>1 cm) fluid-filled blister; clear fluid. |
| Pustule | Small or large pus-filled blister; white or yellow fluid. |
| Cyst | Small or large nodule with epithelial-lined central cavity containing solid, semisolid, or fluid-filled material. |
| Erosion | Shallow defect limited to epidermis; the base of the defect may be red or covered by yellow crust. Erosions heal without scarring. |
| Ulcer | Deep defect through the epidermis into the dermis; the base may be red or covered by yellow, blue, or black crust. Ulcers heal with scarring. |
| Fissure | Thin (<2 mm wide), linear erosion into or through the epidermis. |
| Scale | Gray or silver keratin proteins on the tissue surface that become white when moist; usually feels rough on palpation. |
| Crust | Yellow, granular material overlying erosions; develops due to solidification of plasma proteins when the water component of plasma evaporates; crusts overlying ulcers may be blue or black due to heme pigment. |
| Excoriation | Linear or angular erosions due to scratching. |
| Lichenification | Red or skin-colored plaques with exaggerated skin markings due to chronic rubbing; excoriations are usually also present. The surface may be white when moist. |
| Eczema | Erythematous, poorly marginated patches and plaques that demonstrate lichenification and/or evidence of epithelial disruption, such as erosions or crust. |
