Description of Primary Skin Lesions
| Macule: A flat, colored lesion, <2 cm in diameter, not raised above the surface of the surrounding skin. A “freckle,” or ephelid, is a prototype pigmented macule. |
| Patch: A large (>2 cm) flat lesion with a color different from the surrounding skin. This differs from a macule only in size. |
| Papule: A small, solid lesion, <0.5 cm in diameter, raised above the surface of the surrounding skin and hence palpable (e.g., a closed comedone, or whitehead, in acne). |
| Nodule: A larger (0.5-5.0 cm), firm lesion raised above the surface of the surrounding skin. This differs from a papule only in size (e.g., a dermal nevomelanocytic nevus). |
| Tumor: A solid, raised growth >5 cm in diameter. |
| Plaque: A large (>1 cm), flat-topped, raised lesion; edges may either be distinct (e.g., in psoriasis) or gradually blend with surrounding skin (e.g., in eczematous dermatitis). |
| Vesicle: A small, fluid-filled lesion, <0.5 cm in diameter, raised above the plane of surrounding skin. Fluid is often visible, and the lesions are translucent [e.g., vesicles in allergic contact dermatitis caused by Toxicodendron (poison ivy)]. |
| Pustule: A vesicle filled with leukocytes. Note: The presence of pustules does not necessarily signify the existence of an infection. |
| Bulla: A fluid-filled, raised, often translucent lesion >0.5 cm in diameter. |
| Wheal: A raised, erythematous, edematous papule or plaque, usually representing short-lived vasodilatation and vasopermeability. |
| Telangiectasia: A dilated, superficial blood vessel. |