Differential Diagnosis for Circular Rash on the Face

• Single most likely diagnosis
  • Erythema migrans (Lyme disease): This is often characterized by a circular, expanding rash that can appear on the face, among other areas, following a tick bite. The rash is usually accompanied by other symptoms such as fever, headache, and fatigue.
• Other Likely diagnoses
  • Ringworm (Tinea faciei): A fungal infection that can cause circular rashes on the face, typically itchy and red. It's more common in children but can occur in adults as well.
  • Granuloma faciale: A rare skin condition that presents with single or multiple, well-defined, reddish-brown plaques or nodules, typically on the face. It's more common in middle-aged men.
  • Lupus miliaris disseminatus faciei (LMDF): A type of granulomatous rosacea that presents with reddish-brown papules in a circular pattern on the face, primarily affecting young to middle-aged adults.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Erythema multiforme: A skin condition characterized by target lesions, which can sometimes appear as circular rashes. It can be a sign of a severe infection or drug reaction and requires immediate medical attention.
  • Leprosy: Although rare in many parts of the world, leprosy can cause skin lesions that might initially appear as circular rashes on the face. Early diagnosis and treatment are crucial to prevent long-term damage.
• Rare diagnoses
  • Sarcoidosis: A condition that can cause skin lesions, including those that might appear as circular rashes on the face, along with systemic symptoms. It's an autoimmune disease that can affect multiple organs.
  • Cutaneous lymphoma: Certain types of lymphoma can manifest with skin lesions, including circular rashes on the face. These are usually accompanied by other systemic symptoms and require a comprehensive diagnostic workup.