Ulcers may be described as dish shaped, punctate, craterous, shallow or deep. It often possible clinically to determine if the ulcerated surface is granulating or poorly healing. Shallow disruptions of the epithelial surface which are not severe enough to damage the basement membrane are referred to as erosions. In many cases it may be difficult to clinically distinguish the depth of these lesions but their presence indicated a disease process targetting epithelial or dermo-epithelial interface. Damage to hair follicles is less serious and hair will regrow once the process has been controlled.
Lesions heal by primary intention and without scarring.
Intraepithelial necrosis or inflammation causes exfoliation. Alternatively, erosions may result from the disruption of superficial pustules, vesicles and bullae. The shape and character of the lesions may again give clues to the type of lesion that preceded them. Erosions evolving from pustules leave round to oval erosions often surrounded by an epidermal collarette. Excoriations are often linear or angular and associated with haemorrhagic crusts.