DISCUSSION
Stevens-Johnson syndrome (SJS) is a severe mucocutaneous reactions, most commonly triggered by medications, Infection and in 1/3 of cases no cause was identified. There is extensive necrosis and detachment of the epidermis [1].
Mucous membranes are usually affected in more than 90% of cases. Both SJS and TEN are distinguished chiefly by severity, based upon the percentage of blisters and erosions [2,3].
Medications are main trigger of SJS especially allopurinol and anti-epileptic medications [4-5].
The pathology of Stevens-Johnson syndrome is incompletely understood. Studies suggested a cell-mediated reaction against keratinocytes leading to necrosis [6].
Drugs can stimulate the immune system by binding to the major histocompatibility complex (MHC) class I and the T cell receptor, The hallmark of SJS is the keratinocyte necrosis, ranging from partial to full-thickness necrosis of the epidermis [7-8].
For patients with suspected drug induced SJS withdrawal of the offending agent may improve the prognosis. In a 1 observational study of 113 patients with SJS, early drug withdrawal reduced the risk of death by 30 percent for each day before the development of blisters and erosions [9]
The main lines of managment include fluid and electrolyte management,wound care, nutritional support, pain control,temperature management, treatment of infections [10-11].
There are no definitive therapies for SJS [12-13]. Several immunosuppressive or immunomodulating therapies have been used in clinical practice, including systemic corticosteroids, intravenous immune globulin (IVIG), cyclosporine, plasmapheresis, and anti-tumor necrosis factor (TNF) monoclonal antibodies.
None of these therapies have been adequately studied in randomized trials except thalidomide, which was found to be harmful [14]
The use of systemic corticosteroids in patients with SJS has not been evaluated in clinical trials and remains controversial [15].
Another immunologically medicated disorders is Mast cell activation syndrome (MCAS), which is one of Mast cell disorders present with signs and symptoms that are caused either by activation of mast cells or by mast cells infiltrating organs [16].
Mast cell activation syndrome (MCAS) was first proposed as a distinct idiopathic disorder in 2010 [17]. Subsequently, the definition of MCAS expanded to also include primary and secondary categories, making ”mast cell activation syndrome” essentially an umbrella term that describes a clinical presentation, rather than a specific diagnosis [18 ].
In our case the patient was diagnosed earlier with mast cell activation syndrome with pruritis and severe skin reaction, two years later prescribed carbamazepine treating trigeminal neuralgia, the history of drug induced immunologically mediated mast cell activation with skin pruritis was missed and patient developed severe form of SJS. Good history taking is crucial if clinically indicated treatment with carbamazepine. We would like to alert all physicians that carbamazepine should be avoided in any patient with a previous history of drug reaction like mast cell activation syndrome.