Fas-Fas ligand pathway of apoptosis has been considered a pivotal step in the pathogenesis of TEN.There are probably two major pathways involved: Cytokines implicated include perforin/granzyme, granulysin, Fas-L and tumour necrosis factor alpha ( TNFα). They have some natural killer cell activity and can probably kill keratinocytes by direct contact. The mechanism has still not been understood and is complex.ĭrug-specific CD8+ cytotoxic lymphocytes can be detected in the early blister fluid. SJS/TEN is a rare and unpredictable reaction to a medication. Nonsteroidal anti- inflammatory drugs ( NSAIDs) (oxicam type mainly).Nevirapine (non-nucleoside reverse transcriptase inhibitor).Anti-convulsants: lamotrigine, carbamazepine, phenytoin, phenobarbitone.Beta-lactam: penicillins, cephalosporins.The drugs that most commonly cause SJS/TEN are antibiotics in 40%. Infections are generally associated with mucosal involvement and less severe cutaneous disease than when drugs are the cause. SJS/TEN has rarely been associated with vaccination and infections such as mycoplasma and cytomegalovirus.No drug is implicated in about 20% of cases.The medications are usually systemic (taken by mouth or injection), but TEN has been reported after topical use.A half-life of a medication is the time that half of the delivered dose remains circulating in the body. It is more often seen with drugs with long half-lives compared to even a chemically similar related drug with a short half-life.More than 200 medications have been reported in association with SJS/TEN. Polymorphisms to specific genes have been detected (eg, CYP2C coding for cytochrome P450 in patients reacting to anticonvulsants).There are HLA associations in some races to anticonvulsants and allopurinol.It is 100 times more common in association with human immunodeficiency virus infection ( HIV).It is slightly more common in females than in males.It can affect all age groups and all races.

Anyone on medication can develop SJS/TEN unpredictably.SJS/TEN is a very rare complication of medication use (estimated at 1–2/million each year for SJS, and 0.4–1.2/million each year for TEN). Using current definitions, it is nearly always caused by medications. SJS/TEN is a rare, acute, serious, and potentially fatal skin reaction in which there are sheet-like skin and mucosal loss. Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are now believed to be variants of the same condition, distinct from erythema multiforme. What are Stevens–Johnson syndrome and toxic epidermal necrolysis?

Phase ten scoring