Erythema Multiforme Differential Diagnosis
The differential diagnosis for erythema multiforme (EM) includes various conditions that can present with similar skin lesions. Here's a categorized list of potential diagnoses:
- Single most likely diagnosis
- Urticaria: This is often considered due to the similar appearance of target lesions in both conditions, but urticaria tends to be more transient and migratory.
- Other Likely diagnoses
- Stevens-Johnson Syndrome (SJS): Although SJS is more severe and involves mucous membranes, the skin lesions can resemble those of EM.
- Toxic Epidermal Necrolysis (TEN): Like SJS, TEN is a more severe condition with widespread skin necrosis, but early stages might be confused with EM.
- Fixed Drug Eruption: This condition can cause similar target-like lesions, often in response to medication.
- Contact Dermatitis: Allergic reactions to substances can lead to skin lesions that might be mistaken for EM.
- 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 earlier, it's crucial to reiterate the importance of distinguishing these conditions due to their high morbidity and mortality rates.
- Autoimmune Bullous Diseases (e.g., Pemphigus, Pemphigoid): These conditions can present with blistering skin lesions and are critical to identify due to their potential for severe complications.
- Rare diagnoses
- Rowell's Syndrome: A rare condition characterized by lupus erythematosus and EM-like lesions.
- Paraneoplastic Pemphigus: A rare autoimmune disorder associated with underlying neoplasms, presenting with severe blistering skin lesions.
- Acute Hemorrhagic Edema of Infancy: A rare condition in infants, characterized by target-like lesions and edema, often resolving spontaneously.
Each of these diagnoses has distinct features, but they can sometimes present similarly to erythema multiforme, making a thorough clinical evaluation and, in some cases, additional diagnostic tests crucial for an accurate diagnosis.