(A) Example of trauma-induced bullous skin lesions (arrows) in the feet of a 2-month-old child diagnosed with EB simplex. Courtesy of Bernard Cohen (Johns Hopkins School of Medicine; photo copyright DermAtlas). (B) Massive skin blistering as seen in a K14-null mouse neonate. Front paws and facial area are severely affected (arrows). (C) A control littermate exhibits intact skin. (D and E) Micrographs from H&E-stained histological sections prepared from front paws of 2-day-old K14-null (D) and wild-type (E) mice. Fluid-filled blisters are obvious in the K14-null sample. Loss of epidermal integrity occurs near the basal layer of keratinocytes, the defining characteristic of EB simplex. The boxed region in E indicates 3 basal keratinocytes. hf, hair follicles. Scale bar: 100 μm.