Differential Diagnosis for Erythema Multiforme
Single Most Likely Diagnosis
- Urticaria multiforme: This condition is often considered in the differential diagnosis of erythema multiforme due to its similar presentation of targetoid lesions, although it tends to be more urticarial and transient.
Other Likely Diagnoses
- Stevens-Johnson Syndrome (SJS): A severe skin and mucous membrane disorder, usually a reaction to medication or infection. It presents with similar target lesions but is distinguished by its involvement of mucous membranes and more severe systemic symptoms.
- Toxic Epidermal Necrolysis (TEN): A life-threatening skin condition, usually triggered by medications, leading to widespread skin necrosis and detachment. While it's more severe than erythema multiforme, the initial presentation can sometimes be confused.
- 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 more localized and recur at the same sites with drug re-exposure.
Do Not Miss Diagnoses
- Staphylococcal Scalded Skin Syndrome (SSSS): Caused by staphylococcal toxins that strip the skin of its outer layer, leading to widespread blistering and peeling. It's crucial to distinguish this from erythema multiforme due to its different treatment approach and potential severity, especially in children.
- Autoimmune Bullous Dermatoses (e.g., Pemphigus, Pemphigoid): These are a group of diseases that cause blistering of the skin and mucous membranes. While they can present differently, some forms may mimic erythema multiforme, and missing these diagnoses could lead to inappropriate treatment and significant morbidity.
Rare Diagnoses
- Rowell's Syndrome: A rare condition characterized by erythema multiforme-like lesions in association with lupus erythematosus. It's distinguished by the presence of other systemic lupus symptoms and specific immunological findings.
- Paraneoplastic Pemphigus: A rare autoimmune disorder associated with underlying neoplasia, presenting with severe mucosal lesions and skin blistering. It's a diagnosis that should be considered in patients with unexplained, severe blistering diseases, especially with a known history of cancer.
- Acute Hemorrhagic Edema of Infancy: A rare condition seen in infants, characterized by the sudden onset of purpura, edema, and target-like lesions. It's self-limiting but can be alarming in its presentation, necessitating differentiation from more serious conditions like erythema multiforme.