History:

Acne keloidalis isn’t really a variant of acne. It is a type of staph folliculitis, particularly seen around the back of the neck, in African Americans and associated with scarring.
Virtual Slide Histology will show abscesses adjacent to hair follicles. Sometimes there are more plasma cells seen. Ultimately there is dermal fibroplasia and scarring with destruction of hair follicles.

See the illustrated clinical case in Global Skin atlas