Differential Diagnosis for Chronic Inflammatory Arthritis
When approaching a patient with chronic inflammatory arthritis, it's crucial to consider a broad range of potential diagnoses due to the overlapping clinical presentations. Here's a structured differential diagnosis:
Single Most Likely Diagnosis
- Rheumatoid Arthritis (RA): This is often the first consideration due to its high prevalence among chronic inflammatory arthritides. RA typically presents with symmetric polyarthritis, morning stiffness, and can include systemic symptoms like fatigue and fever. The presence of rheumatoid factor (RF) and anti-citrullinated protein antibody (anti-CCP) can support this diagnosis.
- Psoriatic Arthritis: Especially in patients with a history of psoriasis or those presenting with asymmetric oligoarthritis, dactylitis, or enthesitis. The presence of psoriatic skin or nail changes is a strong clue.
Other Likely Diagnoses
- Connective Tissue Diseases (CTD) like Systemic Lupus Erythematosus (SLE): SLE can present with arthritis, but it's often accompanied by other systemic features such as malar rash, nephritis, or hematologic abnormalities. The presence of antinuclear antibodies (ANA) is a key diagnostic clue.
- Crystal-induced Arthropathies (Gout, Pseudogout): These conditions can cause acute or chronic arthritis and are diagnosed based on the identification of crystals in the joint fluid. Gout often presents with sudden, severe monoarthritis, typically affecting the first metatarsophalangeal joint.
- Adult-onset Still's Disease: Characterized by high fevers, rash, and arthritis, often with significant systemic symptoms. The diagnosis is considered when other causes of fever and arthritis have been excluded.
Do Not Miss Diagnoses
- Systemic Vasculitis: Conditions like Giant Cell Arteritis or Polyarteritis Nodosa can present with arthritis but are critical to diagnose due to their potential for serious organ damage. Symptoms such as headache, visual disturbances, or neuropathy can be indicative.
- Myositis: Inflammatory muscle diseases like Polymyositis or Dermatomyositis can present with muscle weakness and sometimes arthritis. Skin manifestations in dermatomyositis are a key diagnostic feature.
- SLE with renal involvement: Given the potential for severe kidney damage, it's crucial to identify SLE early, especially if there are signs of nephritis or other systemic involvement.
Rare Diagnoses
- Relapsing Polychondritis: A rare condition characterized by recurrent episodes of cartilaginous inflammation, which can mimic rheumatoid arthritis but also involves the ears, nose, and trachea.
- Sjögren's Syndrome: An autoimmune disorder that primarily affects the exocrine glands, particularly the salivary and lacrimal glands, but can also cause arthritis.
- Mixed Connective Tissue Disease: Overlaps with features of SLE, scleroderma, and polymyositis, making it a diagnosis of exclusion based on specific autoantibodies and clinical presentation.
Each of these diagnoses requires careful consideration of clinical presentation, laboratory findings, and sometimes imaging or biopsy results to accurately diagnose and manage chronic inflammatory arthritis.