Every medical student has three categories of topic division
- Diseases seen in everyday life
- Diseases which may be seen at least once or will commonly be discussed
- Diseases which are learnt only for the exams
Category 3 catches you by surprise when it makes it an entry in the ED and serves as a reminder of why it is essential always to know something about everything. Stevens-Johnson Syndrome was one of those for me. Although rare, dermatological emergencies are essential to spot and can be life-threatening if left untreated.
Stevens-Johnsons Syndrome is a rare type 4 hypersensitivity reaction which affects <10% of body surface area. It is described as a sheet-like skin loss and ulceration (separation of the epidermis from the dermis).
Toxic epidermal necrosis and Stevens-Johnsons Syndrome can be mixed. However, distinguishing between both disease can be done by looking at % of body surface area involvement.
- < 10% BSA = Stevens-Johnsons Syndrome
- 10-30% BSA = Stevens-Johnsons Syndrome/Toxic epidermal necrosis overlap syndrome
- > 30%= Toxic epidermal necrosis – above image is an example of toxic epidermal necrosis.
Pathophysiology is unknown
Pathophysiology is not clearly known; however, some studies show it is due to T cells’ cytotoxic mechanism and altered drug metabolism.
Causes
The most common cause of Stevens-Johnsons Syndrome is medications. Examples are allopurinol, anticonvulsants, sulfonamide, antiviral drugs, NSAIDs, salicylates, sertraline and imidazole.
As one of the commonest cause is drug-induced, it is a vital part of history taking. Ask direct and indirect questions regarding drug intake, any new (started within 8 weeks) or old medications and previous reactions if any.
Other causes are malignancy and infections (Mycoplasma pneumonia, Cytomegalovirus infections, Herpesvirus, Hep A).
Risk Factors
The disease is more common in women and immunocompromised patients (HIV, SLE)
Clinical Presentations
- Flu-like symptoms(1-14 symptoms)
- Painful rash which starts on the trunk and spreads to the face and extremities.
- Irritation in eyes
- Mouth ulcers or soreness
Clinical Exam Findings
- Skin manifestation – Starts as a Macular rash that turns into blisters and desquamation.
- An important sign in SJS is Nikolsky’s sign: It is considered positive if rubbing the skin gently causes desquamation.
- 2 types of mucosa are involved in SJS – oral and conjunctiva, which precede skin lesions.
- Other findings in the examination may include –
- Oral cavity – ulcers, erythema and blisters
- Cornea – ulceration
Diseases with a similar presentation – in children, staphylococcal scalded skin syndrome can be suspected as it has a similar presentation and can be differentiated with the help of a skin biopsy.
Diagnosis
Clinical awareness and suspicion is the cornerstone step for diagnosis. Skin Biopsy shows subepidermal bullae, epidermal necrosis, perivascular lymphocytic infiltration, which help for definitive diagnosis.
Management
Adequate fluid resuscitation, pain management and monitoring of electrolytes and vital signs, basic supportive or resuscitative actions are essential, as with any emergency management.
The next step is admitting the patient to the burn-unit or ICU, arranging an urgent referral to dermatology and stopping any offending medications. If any eye symptoms are present, an ophthalmology referral is required.
Wound management is essential- debridement, ointments, topical antibiotics are commonly used to prevent bacterial infections and ease the symptoms.
Complications
- Liver, renal and cardiac failure
- Dehydration
- Hypovolemic or septic shock
- Superimposed infection
- Sepsis
- Disseminated intravascular coagulation
- Thromboembolism
- Can lead to death if left untreated
Prognosis
Prognosis of a patient with Stevens-Johnson Syndrome is assesed by the SCORTEN Mortality Assesment Tool. Each item equal to one point and it is used within the 24 hours of admission.
• Age >/= 40 years (OR 2.7)
• Heart Rate >/= 120 beats per minute (OR 2.7)
• Cancer/Hematologic malignancy (OR 4.4)
• Body surface area on day 1; >10% (OR2.9)
• Serum urea level (BUN) >28mg/dL (>10mmol/L) (OR 2.5)
• Serum bicarbonate <20mmol/L (OR 4.3)
• Serum glucose > 252mg/dL (>14mmol/L) (OR5.3)
Predicted mortality based on the above total:
- 0-1 Point = 3.2%
- 2 Points = 12.1%
- 3 Points = 35.3%
- 4 Points = 58.3%
- 5 Points = 90.0%
