<\/span><\/h2>\nA skin biopsy<\/span> of erythema multiforme (EM) may show on the epidermis<\/span>\/ \/epithelium<\/span>:<\/p>\n\n- \nApoptotic<\/span> individual keratinocytes<\/span> (cellular<\/span> self-destruction, the earliest histological<\/span> change)<\/li>\n
- hydropic degeneration of basal<\/span> keratinocytes (swollen degenerated cells at the base of the epidermis)<\/li>\n
- Intercellular edema<\/span> (spongiosis<\/span>)<\/li>\n
- Blisters within and below the epidermis\/epithelium<\/li>\n
- \nEpithelial<\/span>\/ \/epidermal<\/span> necrosis<\/span> no large sheets of epidermal necrosis, as seen in Stevens-Johnson syndrome<\/span> \/ \/ toxic<\/span> epidermal necrolysis (SJS\/TEN).<\/li>\n<\/ul>\n
Dermal<\/span> changes may include:<\/p>\n\n- moderate \/ dense perivascular<\/span> lymphocytic<\/span> infiltrate<\/span> in the papillary dermis<\/span> and along the dermal-epidermal junction (DEJ)<\/li>\n
- Superficial skin edema<\/li>\n
- \nEosinophilic<\/span> infiltrators<\/span>.<\/li>\n<\/ul>\n
<\/span>Direct immunofluorescence<\/span> of erythema multiforme<\/span><\/h2>\nDirect immunofluorescence is not specific. Can show statement<\/span> of immune proteins C3 and fibrin<\/span> along the DEJ and IgM, C3 and fibrin around blood vessels<\/span>.<\/p>\n\n
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\n<\/div><\/div><\/div><\/div>\n
<\/span>Proposed mechanisms<\/span><\/h2>\nHerpes simplex associated EM (HSV) is a delayed type hypersensitivity<\/span> (DTH) reaction that develops in response to infection<\/span> in predisposed individuals. The process has been well studied and involves several steps.<\/p>\n\n- HSV infection of keratinocytes, which may or may not lead to signs of clinical infection.<\/li>\n
- CD34+ cells (Langerhans precursor cells) carry HSV DNA<\/span> fragments to distant keratinocytes.<\/li>\n
- HSV gene<\/span> The fragments are expressed in these distant keratinocytes. HSV DNA and HSV-encoded proteins can be detected in the epidermis affected by MS. However, the HSV virus cannot be cultured.<\/li>\n
- HSV-encoded proteins recruit HSV-specific CD4+ helper T cells.<\/li>\n
- CD4+ T cells<\/span> react to HSV antigens<\/span> producing gamma interferon.<\/li>\n
- Gamma interferon initiates a inflammatory<\/span> waterfall resulting in skin eruption<\/span> of MS.<\/li>\n<\/ol>\n
Drug-induced MS involves a different mechanism with elevated tumor<\/span> necrosis factor alpha instead of gamma-interferon and CD8 + cells and not CD4 + T helper cells.<\/p>\n<\/span>Why is EM major now considered to be distinct from SJS\/TEN?<\/span><\/h2>\nEM major can generally be distinguished from SJS\/TEN on a number of clinical criteria.<\/p>\n
\n- skin type injury<\/span> \u2013 the predominant skin lesion of MS is typical and atypical<\/span> objective papules<\/span> and plates<\/span> and not macules<\/span> which develop into shedding sheets of skin as seen in SJS\/TEN. Skin shedding of more than 1% from the body surface area is common in SJS\/TEN but rare in MS.<\/li>\n
- \nDistribution<\/span> of skin lesions: In MS, the lesions are predominantly acral in distribution, ie they start on the hands and feet. In SJS\/TEN the rash starts on the trunk.<\/li>\n
- \nMucous membrane<\/span> participation \u2013 although in major MS more than two mucous<\/span> membranes may be affected, this is less common in MS and is milder (less severe and extent) compared to SJS\/TEN.<\/li>\n
- \nSystemic<\/span> symptoms like fever<\/span> and discomfort<\/span>, are absent or mild in MS but prominent in SJS\/TEN, especially in prodromal<\/span> period. Fever, when present in MS, is mild (<38.5 C) en comparaci\u00f3n con las fiebres altas con SJS \/ TEN. Los pacientes con SSJ \/ NET est\u00e1n sist\u00e9micamente enfermos.<\/li>\n
- Result and forecast<\/span> \u2013 Virtually all MS patients recover without aftermath<\/span>. SJS\/TEN has a significant morbidity<\/span> and mortality.<\/li>\n
- Recurrences: EM can recur frequently while reappearance<\/span> it's rare in SJS\/TEN. Furthermore, EM is predominantly a disease of young adults (median age 24 years), especially men, whereas SJS\/TEN generally affects an older population (median age 45 years).<\/li>\n<\/ol>\n
EM is predominantly a disease of young adults (median age 24 years), especially men, whereas SJS\/TEN generally affects an older population (median age 45 years).<\/p>\n
Other points of distinction.<\/p>\n
\n- Skin biopsy histology: in EM there is more dermis inflammation<\/span> and individual keratinocytes<\/span> necrosis compared to SJS\/TEN showing minimal inflammation and sheets of epidermal necrosis.<\/li>\n
- Triggers: MS is triggered by infection in most cases compared to SJS\/TEN which is mainly caused by medication.<\/li>\n
- Associations: EM is not associated with HIV<\/span>, Cancer<\/span> and connective tissue<\/span> disease, as reported with SJS\/TEN. The associations of tissue type markers are different.<\/li>\n
- Mechanisms: EM involves CD4+ T cells and interferon gamma, while SJS\/TEN involves Fas ligand, tumor necrosis factor alpha, and CD8+ cells.<\/li>\n<\/ol>\n
In most cases, MS can be diagnosed as a distinct entity from SJS\/TEN, although there remain a few patients where the distinction is not as clear cut.<\/p>\n<\/section>","protected":false},"excerpt":{"rendered":"
Histolog\u00eda de eritema multiforme Una piel biopsia de eritema multiforme (EM) puede mostrar en el epidermis\/ \/epitelio: Apopt\u00f3tico individual queratinocitos (celular autodestrucci\u00f3n, la m\u00e1s temprana histol\u00f3gico cambio) Degeneraci\u00f3n hidropica de…<\/p>","protected":false},"author":8,"featured_media":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":{"footnotes":""},"categories":[204],"tags":[],"class_list":["post-8091","wiki","type-wiki","status-publish","format-standard","category-glosario-definiciones"],"_links":{"self":[{"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/wiki\/8091","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/types\/wiki"}],"author":[{"embeddable":true,"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/comments?post=8091"}],"version-history":[{"count":0,"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/wiki\/8091\/revisions"}],"wp:attachment":[{"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/media?parent=8091"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/categories?post=8091"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/doctorhoogstra.com\/en\/wp-json\/wp\/v2\/tags?post=8091"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}