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.