Differential Diagnosis for Bilateral Joint Pain with Positive ANA and RF, Negative Anti-Citrullinated Peptide (CCP)

• Single Most Likely Diagnosis

  • Systemic Lupus Erythematosus (SLE): This diagnosis is likely due to the presence of a positive ANA, which is a hallmark of SLE, along with bilateral joint pain, a common symptom of the disease. The absence of anti-CCP antibodies makes rheumatoid arthritis (RA) less likely, though it doesn't rule it out entirely.

• Other Likely Diagnoses

  • Rheumatoid Arthritis (RA): Although the negative anti-CCP test reduces the likelihood, RA cannot be ruled out solely based on this, as some patients with RA are anti-CCP negative. The presence of RF and bilateral joint pain still makes RA a consideration.
  • Mixed Connective Tissue Disease (MCTD): This condition often presents with overlapping features of SLE, RA, and scleroderma, and patients typically have a high titer of anti-U1 RNP antibodies. The clinical presentation and positive ANA and RF could suggest MCTD.
  • Sjögren's Syndrome: This autoimmune disorder can present with joint pain and is often associated with positive ANA and RF. It primarily affects the exocrine glands, but systemic manifestations can occur.

• Do Not Miss Diagnoses

  • Lymphoma: Certain types of lymphoma can present with autoimmune phenomena, including positive ANA and RF. It's crucial to consider lymphoma in the differential diagnosis due to its potential severity and the need for prompt treatment.
  • Hepatitis C: This viral infection can induce a rheumatoid factor-positive polyarthritis and is also associated with the production of various autoantibodies, including ANA. Hepatitis C is a critical diagnosis not to miss due to its implications for treatment and potential liver disease.
  • Parvovirus B19 Infection: This infection can cause a symmetric polyarthritis that mimics RA and can also induce the production of autoantibodies, including ANA and RF.

• Rare Diagnoses

  • Relapsing Polychondritis: This rare autoimmune disorder can cause joint pain and inflammation, among other symptoms, and may be associated with positive ANA and RF in some cases.
  • Ehlers-Danlos Syndrome, Hypermobility Type: While primarily known for its musculoskeletal manifestations, some patients may develop autoantibodies, including ANA and RF, though this is less common.
  • Autoimmune Hepatitis: This condition can present with a variety of autoimmune phenomena, including positive ANA and RF, and may cause joint pain as part of its systemic manifestations.