The field of dermatology uses specific terms to describe clinical findings. Below are definitions of terms used to describe the most common dermatologic appearances.
Macules: These are small defined areas of color change that are not palpable (ie, flat or sometimes collapsed). Macules tend to be smaller than 1 cm.
Patch: This is a larger (>1 cm) area of color change that is nonpalpable (ie, level with the skin). In essence, a patch is a large macule.
Papules: These are small lesions that are palpable (ie, feels like a bump). They tend to be smaller than 1 cm and can be any color or texture.
Plaque: This is a large (>1 cm) raised area with palpable borders. Basically, it is a large papule with extensions along the edges. Note that the height is not increased. A plaque is large, raised, and flat. Edges can be palpated, and borders are well delineated. Like papules, they can be any color or texture. Often, this represents a confluence of papules.
Nodule: This is a large (>1.5 cm) papule. Unlike plaques, an increase in the lesion’s height is noted.
Vesicles: These are fluid-filled blisters, usually smaller than 1 cm in diameter. A distinct characteristic is that the vesicle collapses when it is incised and the fluid is removed. It can be considered a fluid-filled papule.
Bulla: These are fluid-filled blisters larger than 1 cm in diameter.
Pustules: These are vesicles filled with neutrophils.