To test the ability of palifermin (a recombinant human keratinocyte growth factor) to decrease mucocutaneous injury and to promote epithelial repair in Toxic Epidermal Necrolysis and Stevens-Johnson Syndrome-Toxic Epidermal Necrolysis Overlap, diseases in which there is extensive sloughing of the skin and mucosa, including that of the eyes, gastrointestinal tract, respiratory and genitourinary systems.