Erythema multiforme and toxic epidermal necrolysis: a comparative study.

Erythema multiforme and toxic epidermal necrolysis were considered in the past to be different aspects in the spectrum of a single disease. Using standard histology and immunochemistry we present evidence that the inflammatory infiltrates of erythema multiforme and toxic epidermal necrolysis are strikingly different both in density and nature. Erythema multiforme has a high density cell infiltrate rich in T-lymphocytes. By contrast, toxic epidermal necrolysis is characterized by a cell-poor infiltrate in which macrophages and dendrocytes predominate with a strong immunoreactivity for TNF-alpha. Such differences indicate a distinct pathogenesis for these diseases.