Stevens-johnson Syndrome and Toxic Epidermal Necrolysis: An Overview of Diagnosis, Therapy Options and Prognosis of Patients.

Both Stevens-johnson syndrome (SJS) and Toxic-epidermal necrolysis (TEN) are generally medication-induced pathological conditions that mostly affect the epidermis and mucus membranes. Nearly 1 to 2 patients per 1,000,000 population are affected annually with SJS and TEN, and sometimes these maladies can cause serious life-threatening events. The reported death rates for SJS range from 1 to 5%, and 25 to 35% for TEN. The mortality risk may even be higher among elderly patients, especially in those who are affected by a significant amount of epidermal detachment. More than 50% of TEN patients who survive the illness may experience long-term lower quality of life and lesser life expectancy. The clinical and histopathological conditions of SJS and TEN are characterized by mucocutaneous discomfort, haemorrhagic erosions, erythema, and occasionally severe epidermal separation that can turn into ulcerative patches and dermal necrosis. The relative difference between SJS and TEN is the degree of ulcerative skin detachment, making them two extremes of a spectrum of severe cutaneous adverse drug-induced reactions (cADRs). In the majority of cases, serious drug-related hypercreativities are considered the main cause of SJS & TEN; however, herpes simplex virus and Mycoplasma pneumoniae infections may also produce similar type clinical conditions. The aetiology of a lesser number of cases and their underlying causative factors remain unknown. Among the drugs with a 'greater likelihood' of causing TEN & SJS are carbamazepine (CBZ), trimethoprim-sulfamethoxazole, phenytoin, aminopenicillins, allopurinol, cephalosporins, sulphonamides, antibiotics, quinolones, phenobarbital, and NSAIDs of the oxicam variety. There is also a strong genetic link between the occurrence of SJS and IEN in the Han Chinese population. Such genetic association is based on the human leukocyte antigen (HLA-B*1502) and the co-administration of carbamazepine. The diagnosis of SJS is made mostly on the gross observations of clinical symptoms, and confirmed by the histopathological examination of dermal biopsies of the patients. The differential diagnoses consist of the exclusion of Pemphigus vulgaris, bullous pemphigoid, linear IgA dermatosis, paraneoplastic pemphigus, disseminated fixed bullous drug eruption, acute generalized exanthematous pustulosis (AGEP), and staphylococcal scalded skin syndrome (SSSS). The management of SJS & TEN is rather difficult and complicated, and there is sometimes a high risk of mortality in seriously inflicted patients. Urgent medical attention is needed for early diagnosis, estimation of the SCORTEN prognosis, identification and discontinuation of the causative agent as well as highdose injectable Ig therapeutic interventions along with specialized supportive care. Historical aspects, aetiology, mechanisms, and incidences of SJS and TEN are discussed. An update on the genetic occurrence of these medication-related hypersensitive ailments as well as different therapy options and management of patients is also provided.