Differential Diagnosis for Elevated WBC Count and Neutrophils after Cortisone Injection in the Right Shoulder
- Single most likely diagnosis:
- Septic arthritis or shoulder infection: This is the most likely diagnosis given the recent cortisone injection, which can increase the risk of infection. The elevated WBC count and neutrophils suggest a bacterial infection.
- Other Likely diagnoses:
- Corticosteroid-induced leukocytosis: Cortisone injections can cause an increase in WBC count, including neutrophils, as a side effect. This reaction is usually transient and resolves on its own.
- Reactive arthritis: This is an inflammatory arthritis that can occur after an infection, potentially triggered by the cortisone injection. It might not fully explain the elevated neutrophils but could contribute to the overall clinical picture.
- Gout or pseudogout: These conditions can cause shoulder pain and might be exacerbated by the cortisone injection. However, they would not typically cause a significant elevation in WBC count and neutrophils unless there was an associated infection.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Osteomyelitis: A bone infection that could be a complication of the cortisone injection. It's crucial to consider this diagnosis due to its potential severity and the need for prompt antibiotic treatment.
- Septic bursitis: An infection of the bursae around the shoulder joint, which could be related to the injection site. This condition requires urgent medical attention to prevent serious complications.
- Endocarditis: Although less directly related to the shoulder injection, in patients with certain risk factors (e.g., pre-existing heart conditions), an infection could potentially lead to endocarditis, a life-threatening condition.
- Rare diagnoses:
- Rheumatoid arthritis flare: While cortisone injections are used to treat rheumatoid arthritis, a flare could theoretically occur, though it would not typically cause such a significant increase in WBC count and neutrophils.
- Hematologic malignancy: Certain blood cancers could cause an elevation in WBC count, but this would be an uncommon presentation and not directly related to the cortisone injection.