Erythema Multiforme

Erythema multiforme (EM) is a skin condition characterized by the appearance of distinctive, target-like lesions on the skin. These lesions are often symmetrically distributed and can affect various parts of the body, including the skin and mucous membranes.

Causes and Triggers

The exact cause of erythema multiforme is not always clear, but it is believed to be an immune-mediated reaction. Common triggers include:

• Infections: Herpes simplex virus (HSV), mycoplasma pneumonia, and other viral or bacterial infections can trigger EM.
• Medications: Certain medications, such as antibiotics (e.g., penicillins, sulfonamides), anticonvulsants, and nonsteroidal anti-inflammatory drugs (NSAIDs), can cause EM as an adverse reaction.
• Vaccinations: Rarely, vaccinations can trigger EM.
• Other factors: Hormonal changes, radiation therapy, and certain medical conditions (e.g., inflammatory bowel disease, lupus) may also contribute to the development of EM.

Symptoms

The symptoms of erythema multiforme can vary in severity and may include:

• Characteristic target-like lesions, often with a central red spot surrounded by a pale area and an outer red ring.
• Lesions can be flat or raised and may blister or crust over.
• Skin lesions typically appear on the hands, feet, face, and extremities, but can also affect other areas.
• Mucous membrane involvement: Lesions can occur in the mouth, eyes, genital area, and other mucosal surfaces, leading to symptoms such as oral ulcers, conjunctivitis, or genital ulcers.
• Systemic symptoms: Fever, fatigue, and malaise may accompany the skin lesions.

Classification

Erythema multiforme can be classified into two main types:

• Erythema multiforme minor (EMm): Characterized by a mild, self-limiting course with minimal mucous membrane involvement.
• Erythema multiforme major (EMM) or Stevens-Johnson syndrome (SJS): A more severe form with significant mucous membrane involvement and potential for serious complications.

Diagnosis

The diagnosis of erythema multiforme is primarily based on clinical presentation and medical history. Diagnostic tests may include:

• Skin biopsy: To confirm the presence of characteristic histopathological features.
• Laboratory tests: To identify potential triggers, such as infections or medication reactions.

Treatment

Treatment for erythema multiforme depends on the severity and underlying cause:

• Supportive care: Wound care, pain management, and hydration for mild cases.
• Antiviral or antibacterial medications: To treat underlying infections.
• Corticosteroids: To reduce inflammation in more severe cases.
• Discontinuation of offending medications: If a medication is suspected to be the trigger.

Complications and Prognosis

Potential complications of erythema multiforme include:

• Infection: Bacterial superinfections can occur, particularly in cases with significant mucous membrane involvement.
• Scarring: Lesions can lead to permanent scarring, especially if they are severe or become infected.
• Respiratory distress: In rare cases, EM can affect the respiratory tract and lead to life-threatening complications.

The prognosis for erythema multiforme is generally good, with most cases resolving within 2-4 weeks. However, the condition can recur, and some individuals may experience persistent or severe symptoms.