Acne Keloid: A type of acneiform disorder in which secondary pyogenic infection in and around pilosebaceous structures ends in keloidal scarring. It manifests as persistent folliculitis of the back of the neck associated with occlusion of the follicular orifices. It is most often encountered in black or Asian men.Keloid: A sharply elevated, irregularly shaped, progressively enlarging scar resulting from formation of excessive amounts of collagen in the dermis during connective tissue repair. It is differentiated from a hypertrophic scar (CICATRIX, HYPERTROPHIC) in that the former does not spread to surrounding tissues.Propionibacterium acnes: A bacteria isolated from normal skin, intestinal contents, wounds, blood, pus, and soft tissue abscesses. It is a common contaminant of clinical specimens, presumably from the skin of patients or attendants.Cicatrix, Hypertrophic: An elevated scar, resembling a KELOID, but which does not spread into surrounding tissues. It is formed by enlargement and overgrowth of cicatricial tissue and regresses spontaneously.