| Primary lesions |
| Macule: a sharply circumscribed area showing alterations of color, not appreciably elevated or depressed. |
| Papule: a well-defined elevated lesion of the skin up to 5 mm in diameter. |
| Nodule: solid lesion of the skin or subcutaneous tissue over 5 mm in diameter. |
| Tumor: a large nodule. When a nodule is more than 2 or 3 cm in diameter, it is usually called a tumor. |
| Vesicle (blister): a sharply demarcated, elevated, fluid-containing lesion of the skin, usually less than 6 mm in diameter. |
| Bulla: a larger vesicle. |
| Pustule: a small, usually less than 5 mm, fluid-filled lesion of the skin that contains pus. |
| Wheal (hive, urtica, or welt): an evanescent, elevated, red lesion of the skin. |
| Petechia: a less than 5 mm diameter macule resulting from a deposition of blood into the skin. The term purpura is at times used for lesions of this type that are somewhat larger, which may also be palpable. |
| Ecchymosis: A larger area of discolored skin resulting from bleeding into the skin. |
| Telangiectasis: visibly dilated, superficial, cutaneous blood vessels. |
| Comedo (white or blackhead): a white, gray, or black noninflammatory plug in the follicle. |
| Burrow: a tunnel, tract, or passage in the skin made by such parasites as the mite of scabies and the larvae of larva migrans. |
| Cyst: a noninflammatory collection of fluid or semisolid material surrounded by a well-defined wall. |
| Secondary or consecutive skin lesions |
| Scale: this represents dry exfoliation. |
| Crust (scab): a collection of epidermal debris, serum, pus, etc., dried together to form a hard mass and overlying an area of epithelial injury. |
| Fissure: a crack in the skin. |
| Erosion: a superficial loss of epithelium that heals without a scar formation. |
| Ulcer: the loss of the entire epithelium that may heal with scar formation. |
| Atrophy: a disappearance, or "wasting," of tissues or parts of tissues. |
| Excoriation (scratch mark): a linear area of injury resulting from scratching. |
| Scar: a fibrotic residual of a previous inflammatory process. |
From: Chapter 105, Skin
NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.