Ch 3 - Rheumatology: RA Flashcards
What is Rheumatoid arthritis (RA)?
Systemic autoimmune inflammatory disorder of unknown etiology affecting multiple organ systems
What does RA affect in in joints?
Synovial lining of diarthrodial joints
What happens to joints in chronic RA?
Symmetric erosive synovitis develops in the joints and leads to articular destruction
What is pathognomic of RA?
Joint erosions
What is the most important destructive element of RA?
Pannus formation
What is a pannus?
Membrane of granulation tissue that covers the articular cartilage at joint margins
What do fibroblast-like cells do during pannus formation?
Invade and destroy the periarticular bone and cartilage at joint margins
What is vascular granulation tissue composed of?
Proliferating fibroblasts
Numerous small BV’s
CD4 T-lymphocytes
Collagen fibers w/in phagolysosomes
What are the genetic factors of RA?
– MHC on chr 6
– Class II MHC allele HLA-DR4
What is the epidemiology of RA?
Female to male 2:1
20-60 yo, peak 40-50
What are the classification categories for RA?
- Morning joint stiffness
- Arthritis of >3 joints
- Arthritis of the hand joints
- Symmetric arthritis
- Rheumatoid nodules
- Rheumatoid Factor (RF) +
- Radiographic changes
Describe morning stiffness in RA.
Must last at least 1 hour before maximal improvement
What are the 14 possible joints involved in RA?
Bilateral PIP joints, MCP joints, wrist, elbow, knee, ankle, and MTP joints
What are Rheumatoid nodules?
Subcutaneous nodules over extensor surfaces, bony prominences, or in juxta-articular regions
Describe radiographic changes of RA.
Erosions, bony decalcification, and symmetric joint-space narrowing seen on hand and wrist X-ray
Describe the MC onset pattern of RA.
Insidious (50-70%) Slow onset over weeks to months Diffuse MSK pain Morning stiffness Low grade fever Joint swelling, erythema
Describe synovial fluid in RA.
- Low viscosity
- WBC = 1,000–75,000/mm3
- > 70% PMNs
- Transparent—cloudy
What % of patients with RA are RF +?
85%
Other 15% fulfill other criteria for dx
What are diseases that can have RF +?
SLE Scleroderma Sjögren’s Viral Parasitic Bacterial Neoplasms Hyperglobulinemic
What is the sensitivity and specificity of cyclic citrullinated peptide Abs for RA?
80% sensitivity and 90-95% specificity for RA
What other diseases can cyclic citrullinated peptide Abs be seen in?
Psoriatic arthritis
TB
Autoimmune hepatitis
What are early radiographic findings in RA?
– Soft tissue swelling
– Joint space
What are late radiographic findings in RA?
– Uniform joint space narrowing due to loss of articular cartilage (hips, knees, etc.)
– Axial migration of the hip (protrusio acetabuli)
– Malalignment and fusion of joints
What is seen near attachment of the joint capsule in RA?
Marginal bone erosions
