Stevens-Johnson syndrome and toxic epidermal necrolysis: Clinical sciences

Chapters:

Watch video only

Introduction 0:00–0:50

Stevens-Johnson syndrome, or SJS, and toxic epidermal necrolysis, or TEN for short, are rare immune-mediated mucocutaneous conditions characterized by widespread blistering and sloughing.
The exact cause of these conditions is still not fully understood, but it is thought to involve type 4 hypersensitivity against certain antigens, including different medications and pathogens.
Now, Stevens-Johnson syndrome is associated with less than 10% of epidermal detachment, while in TEN, there's more than 30% of the skin affected.
Finally, the Stevens-Johnson syndrome-TEN overlap describes epidermal detachment of more than 10% but less than 30%.Now, if your patient presents with a chief concern suggesting Stevens-Johnson syndrome or TEN, first, perform an ABCDE assessment to determine if they are unstable or stable.

Unstable0:50–2:14

If unstable, stabilize the airway, breathing, and circulation; obtain IV access, and start IV fluids. Next, put your patient on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry.
Finally, provide supplemental oxygen to maintain oxygen saturation greater than 90%, and don’t forget to discontinue suspected triggering medications.
Here’s a clinical pearl! In severe cases, Stevens-Johnson syndrome and TEN can cause extensive skin damage, which can leave your patient vulnerable to severe dehydration, electrolyte imbalances, severe pain, infections, and hypothermia.
Because of that, these severe cases are often managed in a burn intensive care unit. It’s important to make sure that your patient is properly hydrated and provide them with pain relief medications, like acetaminophen and opioids.
Additionally, encourage sterile handling of the patient to prevent secondary infection and ensure that they’re in a warm area to prevent hypothermia.Now, let’s return to the ABCDE assessment and take a look at stable patients.

Stable 2:14–4:08

In this case, obtain a focused history and physical exam. Your patient will typically report flu-like symptoms, such as fever, usually above 39 degrees Celsius, as well as cough and sore throat.
Additionally, they will report a rapid onset of pain and rashes affecting the skin and the mucosa. Other findings might include chest pain, a recent history of medication changes, infection, or prior drug reaction.
Here’s a high-yield fact! Medications commonly known to trigger Stevens-Johnson syndrome and TEN include anticonvulsants like phenytoin and carbamazepine, antibiotics like sulfonamides, anti-inflammatories like sulfasalazine, and certain NSAIDs.
Additionally, infections associated with Stevens-Johnson syndrome and TEN include Mycoplasma pneumoniae, HIV, Cytomegalovirus, and Herpes infections.
Alright, moving on to the physical exam, which typically reveals an ill-appearing patient with conjunctivitis! In early stages, you will find atypical, flat or slightly raised, painful, dusky target-like lesions.
On the flip side, in advanced stages, you will find widespread erythema, ulcers, and blisters affecting the skin and mucosa of the mouth, eyes, and genitalia.
Next, if lateral pressure to the lesion causes the upper and lower layers of the epidermis to split, your patient has a positive Nikolsky sign, which is suggestive of these conditions.
Finally, if there’s respiratory involvement, you could also hear lung crackles!With these findings, you should suspect Stevens-Johnson syndrome or TEN.

Labs, Blood cultures, Skin biopsy, Imaging4:08–6:16

Your next step is to order labs, including a CBC, CMP, CRP, and ESR. Additionally, you should obtain blood cultures and a skin biopsy.
Finally, if your patient has pulmonary symptoms, you might need to order chest imaging, such as an X-ray or CT scan. The CBC typically reveals elevated white blood cell count, possibly with low hemoglobin and hematocrit.
The CMP might reveal electrolyte imbalances, and elevated BUN and creatinine, indicating potential kidney involvement. You might also notice elevated AST and ALT, suggesting liver damage, and elevated CRP and ESR suggesting an ongoing systemic inflammation.
Additionally, the blood culture results might be positive if there is a secondary bacterial infection. The skin biopsy will reveal epidermal necrosis and inflammation, ranging from superficial in the case of Stevens-Johnson syndrome, to full thickness if your patient has TEN.
Finally, a chest X-ray or CT scan may reveal features of pneumonitis. Here’s another clinical pearl to keep in mind!
The diagnosis of Stevens-Johnson syndrome and TEN is primarily clinical. However, a skin biopsy is often needed if you want to make a definitive diagnosis, or if you suspect other conditions that can mimic Stevens-Johnson syndrome or TEN.
These include erythema multiforme, exanthematous drug eruptions, staphylococcal scalded skin syndrome, and paraneoplastic pemphigus, as well as Acute generalized exanthematous pustulosis or AGEP, and drug reaction with eosinophilia and systemic symptoms or DRESS.
If you have these findings, you can diagnose Stevens-Johnson syndrome or TEN. Now, to differentiate the two, you need to assess the percentage of the affected body surface area.

Assess affected BSA6:16–7:17

You can do this using the Wallace rule of nines. This method divides the body into 11 distinct sections, each representing 9% of the total body surface area.
These sections include the head, right arm, left arm, chest, abdomen, upper back, lower back, and front and back of each leg.
The remaining 1% is for the groin.Now, if the affected body surface area is less than 10%, you can diagnose Stevens-Johnson syndrome, and, if it’s more than 30%, diagnose TEN.
Finally, if the affected body surface area is between 10 and 30%, your patient has a Stevens-Johnson syndrome-TEN overlap.Alright, now, let’s move on to treatment.

Treatment7:17–7:58

First, you should immediately discontinue any potential medication that could be triggering the immune reaction! Next, provide appropriate wound care, as well as adequate hydration, correct potential electrolyte imbalances, and don’t forget to provide adequate nutritional support and pain management.
Depending on the severity, you may consider immunomodulator therapy with steroids, intravenous immunoglobulin, or medications, like cyclosporine.
If the blood culture is positive, don’t forget to start your patient on antibiotics tailored to the blood culture results.
Finally, order a surgical consult for wound care. Alright, as a quick recap… Stevens-Johnson syndrome and TEN are rare immune-mediated mucocutaneous conditions characterized by widespread blistering and sloughing, often triggered by exposure to certain medications or pathogens.

Review7:58–9:03

The diagnosis of Stevens-Johnson syndrome and TEN is typically clinical, but, in some cases, you might need to order additional lab workup and biopsy, which reveals epidermal necrosis and inflammation.
Now, if the affected body surface area is less than 10%, you can diagnose Stevens-Johnson syndrome, and, if it’s more than 30%, diagnose TEN.
Finally, if the affected body surface area is between 10 and 30%, your patient has Stevens-Johnson syndrome-TEN overlap.
Management includes addressing the triggering cause, adequate hydration, correcting potential electrolyte imbalances, adequate nutritional support, pain management, immunomodulatory therapy, and antibiotics.
Finally, obtain a surgical consult for wound care.
Stevens-Johnson syndrome and toxic epidermal necrolysis | Osmosis