Primary lesions
Primary lesions are those lesions that arise de novo and are therefore the most characteristic of the desease process.
| Bulla: a circumscribed, elevated fluid-filled lesion greater than 1 cm in size (e.g. epidermolysis bullosa, bullous impetigo). |
| Macule: a circumscribed, flat lesion with color change up to 1 cm in size that is not palpable (e.g. ash leaf macules, café au lait macules). |
| Nodule: a circumscribed, elevated solid lesion with depth up to 2 cm e.g. cyst. |
| Papule: a circumscribed, elevated solid lesion up to 1 cm in size, elevation may be accentuated with oblique lighting, e.g. Mila, acne, verrucae. |
| Plaque: a circumscribed, elevated, plateaulike, solid lesion greater than 1 cm in size (e.g. psoriasis). |
| Pustule: a circumscribed, elevated lesion filled with purulent fluid, less than 1 cm in size (e.g. erythema toxicum neonatorum, acne). |
| Vesicle: a circumscribed, elevated, fluid-filled lesion up to 1 cm in size (e.g. herpes simplex). |
