Stevens-Johnson syndrome

Stevens-Johnson syndrome
Name	Stevens-Johnson syndrome
Synonyms	SJS
Caption	Characteristic skin lesions
Field	Dermatology, Emergency medicine
Symptoms	Fever, skin pain, blistering, mucous membrane involvement
Complications	Sepsis, Pneumonia, Acute respiratory distress syndrome
Onset	Rapid
Duration	Weeks to months
Causes	Adverse drug reaction, Infection
Risks	HIV/AIDS, Systemic lupus erythematosus, certain HLA alleles
Diagnosis	Based on symptoms, Skin biopsy
Differential	Toxic epidermal necrolysis, Staphylococcal scalded skin syndrome
Prevention	Avoidance of known triggers
Treatment	Supportive care, Intravenous immunoglobulin, Corticosteroids
Prognosis	Mortality 5–15%
Frequency	1–2 per million per year

Stevens-Johnson syndrome is a severe, life-threatening reaction of the skin and mucous membranes. It is considered a medical emergency, often requiring treatment in an intensive care or burn unit. The condition is part of a spectrum of disease that includes Toxic epidermal necrolysis, with the latter involving more extensive skin detachment.

Signs and symptoms

The syndrome typically begins with nonspecific prodromal symptoms such as fever, sore throat, and malaise, resembling an Upper respiratory tract infection. Within days, a painful rash appears, progressing to blisters and widespread epidermal detachment. Severe involvement of the mucous membranes is hallmark, affecting the oral mucosa, conjunctiva, and genital regions. Ocular complications can include corneal ulceration and symblepharon formation, while pulmonary involvement may lead to Bronchiolitis obliterans.

Causes

The most common triggers are adverse drug reactions, with over 100 medications implicated. High-risk agents include allopurinol, anticonvulsants like carbamazepine and phenytoin, certain antibiotics such as sulfonamides and penicillins, and nonsteroidal anti-inflammatory drugs. Infections are also a known cause, particularly *Mycoplasma pneumoniae* and cytomegalovirus. Genetic predisposition is strongly associated with specific human leukocyte antigen alleles, such as HLA-B*1502 in some Asian populations taking carbamazepine.

Pathophysiology

The condition is a type IV hypersensitivity reaction, specifically a cell-mediated cytotoxic process directed against keratinocytes. This leads to extensive apoptosis and necrosis of the epidermis. Key mediators include granulysin released by cytotoxic T cells and natural killer cells, as well as Fas ligand and perforin pathways. The immune response results in the separation of the epidermis from the dermis, a process known as full-thickness skin loss.

Diagnosis

Diagnosis is primarily clinical, based on the characteristic appearance of the rash and mucosal involvement. A skin biopsy for histopathological examination is often confirmatory, showing epidermal necrosis and subepidermal blister formation. The SCORTEN scale, developed from studies like the EuroSCAR study, is used to assess severity and predict mortality. Differential diagnosis includes conditions like pemphigus vulgaris, bullous pemphigoid, and staphylococcal scalded skin syndrome.

Treatment

Immediate withdrawal of the suspected causative agent is critical. Management is largely supportive and best conducted in specialized units such as burn centers or ICUs. This includes fluid resuscitation, analgesia, wound care, and prevention of sepsis. Specific immunomodulatory therapies are controversial but may include intravenous immunoglobulin or corticosteroids. Cyclosporine and etanercept have also been investigated in clinical trials.

Prognosis

The mortality rate is approximately 5–15%, with higher scores on the SCORTEN scale correlating with worse outcomes. Common causes of death include sepsis, acute respiratory distress syndrome, and multi-organ failure. Long-term sequelae are common, particularly chronic dry eye, photophobia, and blindness from ocular involvement, as well as skin pigmentation changes and scarring. Psychological and quality of life impacts are significant for survivors.

Category:Dermatology Category:Immune system disorders Category:Medical emergencies