Differential Diagnosis for Erythema Multiforme
- Single most likely diagnosis
- Urticaria: This condition is often considered in the differential diagnosis due to its similar presentation of skin lesions, although urticaria typically lacks the targetoid appearance characteristic of erythema multiforme.
- Other Likely diagnoses
- Stevens-Johnson Syndrome (SJS): A severe skin and mucous membrane disorder, usually a reaction to medication or infection. It's distinguished from erythema multiforme by the extent of skin detachment and mucosal involvement.
- Toxic Epidermal Necrolysis (TEN): Similar to SJS but with more widespread skin detachment. It's a medical emergency and must be differentiated from erythema multiforme due to its high mortality rate.
- Fixed Drug Eruption: A condition characterized by skin lesions that occur at the same site each time a particular drug is taken. The lesions can resemble those of erythema multiforme but are typically fewer in number and recur at the same sites.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN): Although mentioned under other likely diagnoses, it's crucial to reiterate here due to its potential for high morbidity and mortality if not promptly recognized and treated.
- Autoimmune Bullous Diseases (e.g., Pemphigus, Pemphigoid): These conditions can present with blistering skin lesions and, although less common, can be severe and require specific treatments.
- Rare diagnoses
- Rowell's Syndrome: A rare condition characterized by erythema multiforme-like lesions in association with lupus erythematosus.
- Paraneoplastic Pemphigus: A rare autoimmune disorder associated with underlying neoplasia, presenting with severe mucosal lesions and skin blistering.
- Acute Generalized Exanthematous Pustulosis (AGEP): Characterized by numerous small, sterile pustules on the skin, often accompanied by fever and leukocytosis, typically triggered by medications.