SKINIPEDIA - Skin Diseases: Toxic Epidermal Necrolysis

Skin Diseases and Conditions: Toxic Epidermal Necrolysis

A STUDY by Author: Victor Cohen, PharmD, Clinical Pharmacy Manager, Department of Emergency Medicine, Maimonides Medical Center, Assistant Professor, Division of Pharmacy Practice, Arnold and Marie Schwartz College of Pharmacy and Health Sciences, Long Island University

BACKGROUND

Toxic epidermal necrolysis (TEN) is a potentially life-threatening skin disorder that is most commonly drug induced. However, the disorder has other potential etiologies, including infection, malignancy, and vaccinations. Toxic epidermal necrolysis is idiosyncratic, and its occurrence is not easily predicted. Some authors believe Stevens-Johnson syndrome (SJS; also known as erythema multiforme) is a manifestation of the same process involved in toxic epidermal necrolysis, with the latter involving more extensive necrotic epidermal detachment. (Toxic epidermal necrolysis involves >30% of the body surface, whereas SJS involves <10%.)

Alan Lyell provided an early description of toxic epidermal necrolysis in 1956, describing the condition as "an eruption resembling scalding of the skin."¹ This dermatological condition is characterized by extensive epidermal loss suggestive of severe scalding. In that same year, Lang and Walker also observed a patient with toxic epidermal necrolysis,² which was originally described by Debre et al in 1939 in French as l'erythrodermie bulleuses avec epidermolyse.³ Lyell later reclassified the conditions of two of his patients as another disease, staphylococcal scalded skin syndrome,⁴ which is due to Staphylococcus aureus infection rather than to a probable drug hypersensitivity-type reaction. Histopathologic analysis of the skin remains the main tool for discrimination between the two conditions.

PATHOPHYSIOLOGY

The pathophysiology of toxic epidermal necrolysis has not been fully elucidated; however, various theories have received wide acceptance. Toxic epidermal necrolysis is believed to be an immune-related cytotoxic reaction aimed at destroying keratinocytes that express a foreign antigen.

Toxic epidermal necrolysis mimics a hypersensitivity reaction, with its characteristic delayed reaction to an initial exposure and an increasingly rapid reaction with repeated exposure.

Explanations for the generalized nature of toxic epidermal necrolysis include the belief that tumor necrosis factor-α (TNF-α) is overexpressed in the epidermis. Therefore, TNF-α likely plays an important role in epidermal destruction directly through apoptosis, indirectly through stimulating cytotoxic T lymphocytes, or both.

Frequency - United States

The frequency of toxic epidermal necrolysis is reported to be 0.22-1.23 cases per 100,000 population.

International

The average incidence of toxic epidermal necrolysis is 0.5-1.4 cases per million population per year. In 1992, the cumulative incidence of toxic epidermal necrolysis and SJS in Germany was 1.9 cases per million population. A French survey of dermatologists and health care facilities reported an incidence of 1 case per million population per year.

Toxic Epidermal Necrolysis Study - Morbidity - Part II is here

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