What is the diagnosis for a patient with elevated Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP), negative Rheumatoid Factor (RF) and Antinuclear Antibody (ANA)?

Differential Diagnosis for ESR 42, CRP 38, Negative Rheumatoid Factor, and ANA

Single Most Likely Diagnosis

• Osteoarthritis: Elevated ESR and CRP can be seen in osteoarthritis, especially if there is significant inflammation. The absence of rheumatoid factor and ANA makes rheumatoid arthritis and lupus less likely, pointing towards a more mechanical or degenerative condition like osteoarthritis.

Other Likely Diagnoses

• Polymyalgia Rheumatica (PMR): Characterized by elevated inflammatory markers (ESR and CRP) and muscle pain, PMR is a strong consideration. The absence of rheumatoid factor and ANA does not rule out PMR.
• Seronegative Spondyloarthropathies: Conditions like ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and enteropathic arthritis can present with elevated inflammatory markers without rheumatoid factor or ANA positivity.
• Infections: Certain infections, such as endocarditis, osteomyelitis, or septic arthritis, can cause elevated ESR and CRP. The clinical context and additional symptoms would guide this diagnosis.

Do Not Miss Diagnoses

• Giant Cell Arteritis: A form of vasculitis that can present with elevated ESR and CRP, and is often associated with PMR. It's crucial to consider this diagnosis due to the risk of vision loss if not promptly treated.
• Malignancy: Certain cancers can cause elevated inflammatory markers. Although less common, it's critical not to miss a diagnosis of malignancy, such as lymphoma or multiple myeloma.
• Endocarditis: Infective endocarditis can present with elevated ESR and CRP, and it's essential to consider this diagnosis due to its high mortality rate if untreated.

Rare Diagnoses

• Relapsing Polychondritis: A rare autoimmune disorder that can cause inflammation in various cartilaginous structures, leading to elevated ESR and CRP.
• Sarcoidosis: Although more commonly associated with pulmonary symptoms, sarcoidosis can cause elevated inflammatory markers and should be considered in the differential diagnosis, especially if other systemic symptoms are present.
• Familial Mediterranean Fever: A genetic disorder characterized by recurrent episodes of fever and inflammation, which could explain elevated ESR and CRP in the appropriate clinical context.