Discussion
SJS is a rare adverse drug reaction with a high mortality rate and multi- organ failure. This syndrome is characterized by dusty patches, atypical targetoid lesions, bullae and erosions and epidermal detachment less than 10%. It occurs more often in women unlike our case.
There are various mechanisms by which this syndrome occurs. First of all, after the responsible drug is taken, the drug itself binds to T-cell receptors or MHC class 1 receptors in antigen-presenting-cells (APC). The result is clonal expansion of CD8+ cytotoxic T cells and Natural Killer Cells (NK Cells); leading to epidermal necrosis. Fas-FasL, expressed on the activated cytotoxic T cells, can also destroy keratinocytes via the production of intracellular caspases. In addition, it is thought that nitrous oxide (NO) induced by tumor necrosis factor-α (TNF-α) and interferon (IFN)-alpha may also stimulate caspases.[1] Moreover, recent studies have shown high levels of cytotoxic molecules within lesions of SJS/TEN, such as perforin, granzyme B, and granulysin. [2]
SJS may be caused by either drugs or infections. The most frequently associated drugs are reported as allopurinol, aminopenicillins, cephalosporins, anticonvulsants and NSAIDs. [3] To our knowledge, there is no reported SJS case caused by favipiravir, in the literature. In our case; it is not clear whether the lesions of the patient are caused by Covid-19 infection or by the use of favipiravir.
There are various skin manifestations of COVID-19 reported in the recent literature. Those findings include urticaria, pityriasis rosea-like eruption, chickenpox-like vesicles and chillblain-like lesions.[4] Moreover, SJS-like lesions may be a manifestation of COVID-19 infection, as well. Up to now, there are a few case reports in the literature indicating that Covid-19 disease may be related with SJS. Parlakay et al. reported a case of a pediatric patient, with COVID-19 presenting like SJS. In their case, either amoxicillin-clavulonate treatment given for tonsillitis or COVID-19 infection could be the cause of SJS, as in our case. [5] In addition, it is discussed in a case-report that viral infections such as COVID-19 might induce SJS and susceptibility to drugs may be increased in patients with COVID-19 infection. [6] Despite the fact that, SJS has been linked to drug exposure, infectious agents such as HIV , Mycoplasma pneumonia , Herpes Simplex virus may have an effect on the incidence of SJS. [2] In fact, there is still no evidence that Covid-19 infection is a cause of SJS. We wanted to indicate that, SJS - a very serious adverse drug reaction -may be triggered by either Covid-19 - the very common disease all over the world - or by the very commonly used drug, favipiravir.