Differential Diagnosis for Inflammatory Lymph Nodes in Axilla after Arm Bite
Single Most Likely Diagnosis
- Cat scratch disease: This is a common condition caused by the bacterium Bartonella henselae, typically transmitted through cat scratches or bites. The presentation of inflammatory lymph nodes in the axilla on the same side as the bite, approximately 1 week later, is consistent with cat scratch disease, which often causes regional lymphadenopathy.
Other Likely Diagnoses
- Cellulitis or abscess: Bites can introduce bacteria into the wound, leading to infections like cellulitis or abscess formation. While these conditions primarily cause local signs of infection (redness, swelling, warmth, and pain), they can also lead to lymphadenitis, which is inflammation of the lymph nodes.
- Staphylococcal or streptococcal lymphadenitis: These bacterial infections can cause lymph node inflammation and are common complications of skin infections, including those resulting from bites.
- Pasteurella multocida infection: This bacterium is commonly found in the mouths of dogs and cats and can be transmitted through bites, leading to infections that may cause lymphadenitis.
Do Not Miss Diagnoses
- Rabies: Although rare in many parts of the world, rabies is a deadly viral disease that can be transmitted through the bites of infected mammals. Early symptoms can be non-specific, but the disease is almost always fatal if not treated promptly after exposure.
- Tetanus: Caused by the bacterium Clostridium tetani, tetanus can be introduced into the body through wounds, including bites. It leads to severe muscle stiffness and spasms and can be fatal if not treated.
Rare Diagnoses
- Erysipeloid: A bacterial infection caused by Erysipelothrix rhusiopathiae, typically acquired through contact with infected animals or contaminated animal products. It can cause a distinctive skin lesion and may lead to lymphadenitis.
- Capnocytophaga canimorsus infection: This bacterium is found in the mouths of dogs and can cause severe infections in humans, particularly those with compromised immune systems, following a dog bite.
- Actinomycosis: A chronic bacterial infection that can cause abscesses and lymphadenitis, although it is more commonly associated with oral or gastrointestinal infections.