Differential Diagnosis for Cat Scratch
- Single most likely diagnosis
- Cat scratch disease (Bartonellosis): This is the most likely diagnosis due to the direct exposure to a cat scratch, which is a common mode of transmission for Bartonella henselae, the bacterium responsible for cat scratch disease.
- Other Likely diagnoses
- Cellulitis: A bacterial infection of the skin and subcutaneous tissues, which can occur after a cat scratch, especially if the scratch becomes contaminated with bacteria.
- Abscess: A localized collection of pus that can form after a cat scratch, particularly if the wound becomes infected.
- Folliculitis: An inflammation of the hair follicles, which can occur after a cat scratch, especially if the scratch introduces bacteria into the follicles.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Rabies: Although rare, rabies can be transmitted through a cat scratch if the cat is infected, making it a critical diagnosis not to miss due to its high mortality rate if left untreated.
- Tetanus: A bacterial infection caused by Clostridium tetani, which can enter the body through a wound like a cat scratch, especially in individuals who are not up-to-date on their tetanus vaccinations.
- Rare diagnoses
- Pasteurella multocida infection: A bacterium commonly found in the mouths of cats and dogs, which can cause infections in humans through bites or scratches, though it's less commonly associated with scratches than bites.
- Capnocytophaga canimorsus infection: A bacterium found in the mouths of cats and dogs, which can cause severe infections in humans, particularly those who are immunocompromised, though it's more commonly associated with dog bites than cat scratches.
- Erysipeloid: A bacterial infection caused by Erysipelothrix rhusiopathiae, which can be transmitted through contact with infected animals, including cats, though it's more commonly associated with occupational exposure (e.g., butchers, veterinarians).