Mucosal disease series. Number IV. Erythema multiforme

Area of Science:

• Dermatology
• Immunology
• Pathology

Background:

• Erythema multiforme (EM) is an acute, mucocutaneous hypersensitivity reaction presenting as skin eruptions, potentially with oral or mucosal lesions.
• EM variants are classified by mucosal involvement and skin lesion characteristics, including EM minor (most common, one mucosa) and EM major (more severe, multiple mucosae).
• Distinguishing EM major from Stevens-Johnson syndrome (SJS) is crucial due to SJS's higher morbidity and mortality.

Purpose of the Study:

• To elucidate the classification and clinical distinctions of Erythema multiforme (EM) variants.
• To differentiate EM major from Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN).
• To outline the known triggers and underlying immune mechanisms of EM, SJS, and TEN.

Main Methods:

• Review of existing literature on Erythema multiforme, Stevens-Johnson syndrome, and Toxic Epidermal Necrolysis.
• Comparative analysis of clinical presentations, diagnostic criteria, and etiological factors.
• Examination of immunological pathways involved in mucocutaneous reactions.

Main Results:

• EM minor typically involves one mucosa with target lesions; EM major affects multiple mucosae with variable skin lesions.
• EM major shares features with SJS, but SJS presents with extensive skin involvement and higher mortality (5-15%).
• Herpes simplex virus (HSV) is a documented trigger for EM via cell-mediated immunity; drugs often trigger SJS/TEN through soluble factors like Fas/FasL.

Conclusions:

• EM encompasses a spectrum of mucocutaneous reactions with distinct clinical and etiological profiles.
• Accurate differentiation between EM major, SJS, and TEN is critical for patient management and prognosis.
• Understanding the immune response to triggers like HSV and drugs is key to managing these hypersensitivity reactions.