Associated with HLA-DR_w4 in 91% (Lancet 1979;2:441); paraneoplastic type with lymphoma (Nejm 1990;323:1729)

Si:Can push blister fluid into new areas of skin (Nikolsky's sign); normal skin sloughs and forms bullae when rubbed; middle age onset; scalp, mucosal membranes, and flexor surfaces primarily involved; "baggy blisters" because overlying epidermis is very thin, rarely hemorrhagic

Rx:Steroids, and follow antibody titers; cyclophosphamide; azathioprine; or nicotinamide and tetracycline (J Am Acad Derm 1993;28:998); iv immunoglobulin and rituximab (Nejm 2006;355:1772)