Differential Diagnosis for Erythema Migrans with Blisters in the Middle
- Single most likely diagnosis
- Lyme disease: This is the most likely diagnosis due to the characteristic presentation of erythema migrans, which is a rash that often appears in the early stage of Lyme disease. The presence of blisters in the middle could be a variation of the typical bull's-eye rash.
- Other Likely diagnoses
- Southern tick-associated rash illness (STARI): This condition presents with a similar rash to erythema migrans but is caused by a different tick-borne illness. The rash can have a central blister.
- Erythema multiforme: This is an immune-mediated condition that can cause target-like lesions, which might resemble erythema migrans with blisters in the middle.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Rocky Mountain spotted fever (RMSF): Although less common, RMSF can present with a rash that might be confused with erythema migrans. It's a severe and potentially fatal disease if not treated promptly.
- Tularemia: This bacterial infection can cause a skin ulcer or rash at the site of the tick bite, which might be mistaken for erythema migrans with blisters.
- Rare diagnoses
- Tick-borne relapsing fever: This condition is caused by certain species of Borrelia and can present with a rash, although it's less common and typically associated with fever and other systemic symptoms.
- Babesiosis: While primarily known for causing a malaria-like illness, babesiosis can occasionally present with a rash, although this is rare and usually accompanied by more severe systemic symptoms.