Epidermolysis bullosa simplex. A new histologic subgroup.

Two patients with a new mechanobullous disease are described. The trauma-induced bullae were present at birth. The nails were deformed in both cases. Both patients were isolated cases; so far, the inheritance pattern is not known. The histologic picture was unique. The keratinocytes were dyskeratotic, enlarged, and had atypical mitoses on light microscopy of neonatal biopsy specimens. Electron microscopically the defect occurred in the tonofilaments, which formed round clumps. The blister formation took place in the lower part of the epidermis.