SJS is an acute immunological mucocutaneous disorder with a high mortality and morbidity rate that may affect patients at any age. However, the children are known to be affected less severely, and the mortality rate is around 7.5%. SJS and TEN are considered two similar entities of the same disease spectrum, differing only in the severity of skin detachment. The distinction is mainly based on the involved body surface area .
The most known cause of the disease is the usage of drugs, accounting for approximately 80% of the cases. Even though the pathogenesis of the disease is not fully understood, it is now known that it happens as a result of a cumulative effect of the drug’s structure and the patient’s genetic predisposition. There are many defined genetic associations between the drugs, Human Leukocyte Antigen (HLA) alleles, cytochrome p450 (CYP) pathways, and various ethnicities . In a study that reviewed the causes of SJS and TEN in children by Ferrrandiz-Pulido et al., it was stated that the drugs that cause SJS vary, and the main ones are sulphonamides and anticonvulsants, followed by penicillins and nonsteroidal anti-inflammatory drugs. Mycoplasma and herpes virus infections are also common causes in childhood .
The diagnosis of SJS is confirmed by the histopathologic examination of a biopsy of the characteristic skin lesions that are diffuse erythematous macules with purpuric, necrotic centers with blisters. The hypersensitivity reaction results in widespread inflammation of the epidermis, leading to necrosis, blistering, and sloughing of the tissue. In early lesions, scattered necrotic keratinocytes are seen in the epidermis with mild superficial perivascular mixed inflammatory dermal infiltrate, and as the blisters start to form in later stages, full-thickness epidermal necrosis is seen with basal vacuolar change, subepidermal bullae, and mild superficial perivascular mixed inflammatory dermal infiltrate [6, 7].
There is an involvement of mucous membranes in approximately 90% of the affected patients, and the lip, oral cavity, conjunctiva, nasal cavity, urethra, vagina, gastrointestinal tract, and/or respiratory tract may be affected as lesions develop. Ophthalmic involvement is common and develops in approximately 50–60% of hospitalized patients . In a retrospective analysis by Chang et al., 60% of the patients with SJS/TEN developed ocular involvement during the acute phase of the disease . Clinically, acute and extensive ocular surface inflammation occurs with the pseudomembranous formation and corneal or conjunctival epithelial defects resulting in dry eye disease, corneal and conjunctival scarring, and symblephera formation. The most common ocular feature of SJS is the loss of corneal epithelial stem cells located in the limbal area, which is confirmed by the loss of palisades of Vogt. With the loss of the stem cells during the acute phase of the disease, the corneal epithelium stops regenerating, resulting in “conjunctivalization,” which can be defined as a conjunctival epithelial invasion into the cornea . This feature can be indicated histopathologically by the presence of the Goblet cells in the cornea.
In a study by Lopez-Garcia et al., histopathologic and cytologic changes were recorded during the acute phase and then six months later. They concluded that epithelial cell squamous metaplasia was related to ocular involvement severity in the acute phase and conjunctival cytological samples showed a marked decrease in goblet cell density as the lesions subsided .
Corneal involvement then may result in cicatricial, sclerotic changes of the ocular surface and changes such as neovascularization, opacification, keratinization, and even ulceration and perforation. After the acute phase, some of these changes may subside; however, there may be permanent visual impairment and conjunctival inflammation that prolong at the chronic stage .
Detailed clinical information and histopathological appearance constitute the strengths of the case.
In conclusion, Stevens-Johnson syndrome affects various mucous membranes along with the skin. Therefore, ocular involvement is an essential factor that causes morbidities, and a careful clinical and histopathologic examination is required in order to give the correct diagnosis.