These phagocytic histiocytes carry away the foreign substances and debris, usually via vascular channels, but in the perforating diseases, via direct extrusion. The repair process follows close behind, with neovascularization and fibrosis. The duration of such a project is highly variable, often taking years to complete. A rare systemic version is fatal, in which abnormal elastic tissue is found in the walls of ruptured blood vessels and viscera. No racial differences have been reported.
Small papules erupt and are grouped in a confined area, eventually becoming serpiginous.
The central core of each papule contains a compressed aggregate of fibrous material and cellular debris that, eventually, is disgorged to the surface, after which the papule subsides and disappears. EPS usually is asymptomatic but can be pruritic. Secondary lesions are vague scars or areas of roughness and hypopigmentation or hyperpigmentation that result after the primary lesions have subsided and disappeared. Three general categories of EPS are recognized. Inciting events are not known.