Most commonly they are of adnexal or follicular origin. S These are often regarded as secondary lesions, but can be thought of as ruptured, peripherally spreading pustules, vesicles or bullae, giving rise to the appearance of a ring of scale. There are often spreading zones of accompanying erythema, and central healing and post-inflammatory pigmentation is common. Erosion S Loss of epidermis with the basal layer remaining intact. Often occur when intraepidermal vesicles and bullae rupture.
Healing occurs without scar formation.
This is superficial loss of epidermis often due to self trauma secondary to pruritus. They are often linear. Hyperemia P,S Hyperemia occurs when arterial and arteriolar dilatation produces an increased flow of blood into capillary beds. In other words, hyperemia is an active process. As would be expected, there is increased redness in the affected area.