Acne Keloidalis

Case 750 (H. Diwan) 40 years-old Hispanic male with 5mm firm lesion on posterior left scalp. Clinical impression: nevus sebaceus.

Numerous naked hair shaft foreign body granulomas (some with partially degraded hair shafts); plasma cells and fibrosis, no significant acute inflammatory component.  A central follicle shows tapering exclamation-point features, dysmorphic hair shaft, polytrichia, concentric lamellar fibroplasia and atrophy extending deep into the infundibulum.  

Case 2659 (U. Sundram) 55 year old male with recurrent cystic lesions in the posterior occipital scalp. Excision of EIC.

Suppurative peri-folliculitis and scarring.

Case 4013 (H. Diwan) 53 year-old male with pink papules on posterior neck.

Perforating folliculitis with foreign-body reaction to extruded keratin.  Plasma cells.