Differential Diagnosis for Bullseye Lesions

• Single most likely diagnosis
  • Erythema multiforme: This condition is characterized by target-like lesions, often referred to as "bullseye" lesions, which are typically seen on the skin and sometimes on the mucous membranes. The lesions are usually symmetrically distributed and can be triggered by infections, medications, or other factors.
• Other Likely diagnoses
  • Fixed drug eruption: This is a type of skin reaction that occurs at the same site every time a particular drug is taken. The lesions can resemble bullseye targets and are often seen in response to certain medications.
  • Lyme disease (erythema migrans): The initial stage of Lyme disease can present with a characteristic "bullseye" rash, known as erythema migrans, which is a expanding red patch with a central clearing.
  • Urticaria: While not always bullseye in appearance, some cases of urticaria can present with target-like lesions, especially when caused by certain infections or allergic reactions.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Meningococcemia: This is a severe infection caused by Neisseria meningitidis, which can present with a petechial or purpuric rash that may resemble bullseye lesions in some cases. It is a medical emergency that requires prompt treatment.
  • Rocky Mountain spotted fever: This tick-borne illness can cause a rash that may appear as bullseye lesions, and it is essential to recognize and treat it promptly to prevent severe complications.
• Rare diagnoses
  • Sweet syndrome: A rare condition characterized by fever, leukocytosis, and tender, erythematous skin lesions that can sometimes resemble bullseye targets.
  • Erythema gyratum repens: A rare skin condition associated with underlying malignancies, which can present with wavy, circular lesions that might be mistaken for bullseye lesions.
  • Leukocytoclastic vasculitis: A type of blood vessel inflammation that can cause skin lesions, including those that might resemble bullseye targets, although this is less common.