Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe immune-mediated mucocutaneous reactions characterized by epidermal detachment and necrosis, almost always secondary to drugs. 

SJS and TEN are no longer considered separate pathologies and are instead distinguished by percentage of body surface affected by blisters and erosions. SJS involves skin detachment of less than 10% of the body surface, while TEN involves detachment of more than 30% of the body surface area. Patients with skin detachment of 10 to 30% of BSA are considered to have SJS/TEN overlap. Early diagnosis and treatment are crucial in managing SJS/TEN as up to 10% of SJS cases and less than 30% of TEN cases are fatal. 

Erythema multiforme (EM) is an immune-mediated mucocutaneous reaction following infection (most often HSV type 1) characterized by target lesions with bullae or erosions. Other symptoms include fever, asthenia, arthralgia, and pneumonia-like symptoms.

In this learning module, you will find a key point review on SJS, TEN, and EM focused on epidemiology, pathogenesis, clinical features, pathology, differential diagnosis and management. To test your knowledge, we refer you to the associated Quiz (short answer format questions) and clinical vignettes simulating OSCE examinations. We hope you find this module useful and if you choose to submit new questions or vignettes to increase the content of this module or post comments on how we can improve this module for your learning, we look forward to them.

Select how you would like to proceed below:

1. Bolognia, J., Cerroni, L., & Schaffer, J. V. (2018). Dermatology. Philadelphia: Elsevier.
2. Wolverton, S. E. (2013). Comprehensive dermatologic drug therapy. Edinburgh: Saunders.