Author: Dr Delwyn Dyall-Smith, Dermatologist, 2009.
Dermal changes may include:
Direct immunofluorescence is not specific. It may show deposition of immune proteins C3 and fibrin along the DEJ and IgM, C3 and fibrin around blood vessels.
Herpes simplex(HSV)-associated EM is a delayed type hypersensitivity (DTH) reaction that develops in response to infection in predisposed individuals. The process has been well studied and involves a number of steps:
Drug-induced EM involves a different mechanism with elevated tumour necrosis factor alpha rather than gamma-interferon and CD8+ cells and not CD4+ T helper cells.
EM major can usually be distinguished from SJS/TEN on a number of clinical criteria:.
In addition, EM is predominantly a disease of young adults (median age 24 years), especially males, whereas SJS/TEN typically affects an older population (median age 45 years).
Other points of distinction.
In the majority of cases, EM can be diagnosed as a distinct entity from SJS/TEN although there remain some patients in whom the distinction is not so clearcut.
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