M08.027.002 Rheumatoid arthritis (RA)

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease characterized by progressive inflammation of the joints, production of autoantibodies like rheumatoid factor, and involvement of organs beyond the joints. Understanding the disease process, clinical presentation and potential complications is crucial for medical students.

Description

• Autoimmune disease: The immune system mistakenly attacks the body’s own tissues, in this case, the synovial lining of joints.
• Chronic: Symptoms persist for months or years.
• Systemic: Can affect various organs throughout the body.
• More common in females: Affects women roughly four times more often than men.
• Onset: Typically occurs between ages 20-50.
• Genetics: HLA-DR4 and HLA-DR1 genes increase susceptibility, but are not a definitive cause.

Points to Remember:

• The exact cause of RA remains unknown, but a combination of genetic and environmental factors is likely involved.
• Early diagnosis and treatment are critical to minimize joint damage and improve long-term outcomes.

Clinical Features

• Joint involvement:
  • Typically affects the hands, wrists, knees, and ankles in a symmetrical pattern.
  • Morning stiffness that improves with activity is a common complaint.
  • Joints may exhibit:
    • Fusiform swelling (spindle-shaped enlargement)
    • Redness
    • Warmth
    • Particularly affects the proximal interphalangeal (PIP) joints
• Joint Deformities:
  • Develop over time due to chronic inflammation and synovial proliferation.
  • Examples include:
    • Radial deviation of the wrist and ulnar deviation of the fingers
    • Swan-neck deformity (hyperextended PIP joint and flexed DIP joint)
    • Boutonniere deformity (flexed PIP joint and extended DIP joint)
• Baker’s cysts: Fluid-filled sacs that may form behind the knee.

Imaging:

• An X-ray may show:
  • Juxta-articular osteoporosis (bone loss near the joint)
  • Bone erosions
  • Joint effusion (fluid buildup)

Laboratory Findings

• Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels, indicating inflammation.
• Hypergammaglobulinemia (increased levels of immunoglobulins, proteins involved in the immune response).
• Rheumatoid factor (RF): An autoantibody found in about 80% of RA cases. Its titer may correlate with disease severity.

Extra-articular Manifestations

• RA can affect various organ systems beyond the joints.
• Systemic symptoms may include:
  • Low-grade fever
  • Malaise (general feeling of unwellness)
  • Fatigue
  • Lymphadenopathy (swollen lymph nodes)
  • Weakness
• Vasculitis: Inflammation of blood vessels due to immune complex deposition.
• Rheumatoid nodules: Firm, painless bumps under the skin, often on extensor surfaces of forearms and elbows. Can also occur in internal organs.
• Sjögren’s syndrome: An autoimmune disorder causing dryness of the eyes and mouth, which can coexist with RA.
• Felty’s syndrome: RA accompanied by an enlarged spleen (splenomegaly) and low white blood cell count (neutropenia).
• Caplan syndrome: RA associated with lung inflammation (pneumoconiosis).
• Secondary amyloidosis: A rare complication where abnormal protein deposits in various organs can occur in severe, long-standing RA.

Summary of Rheumatoid Arthritis Characteristics

Bibliography

• Kumar, Vinay, et al. Robbins Basic Pathology. Elsevier, 2018.
• Fauci, Anthony S., et al. Harrison’s Principles of Internal Medicine. McGraw-Hill Education, 2018.
• https://www.mayoclinic.org/diseases-conditions/rheumatoid-arthritis/symptoms-causes/syc-20353648pen_spark