Rheumatology Made Ridiculously Simple

Lasering In On Lupus

Systemic Lupus Erythematous (SLE)is an autoimmune disease with a wide range of clinical presentations. This makes SLE a difficult disease to diagnose, since its manifestations vary.

The simplest way to discuss the disease is with a systems approach, considering how SLE can involve each system individually, and then begin to put the clues together.

Gout vs. Pseudogout

Polarized microscopy is critical in evaluating a patient with suspected crystalline arthritis. When a patient presents with acute swelling and pain in a single joint, fluid can be drained (arthrocentesis). Then a sample of synovial fluid is placed under a microscope and illuminated with polarized light that is traveling in a known direction across the sample.

Crystals within the synovial fluid will reflect light differently (and therefore be either blue or yellow in color) depending on their composition and can be categorized as either positively or negatively birefringent. Shape of the crystals is also an important factor.

Gout = Negatively birefringent (yellow parallel with polarized light), needle-shaped

Pseudogout = Positively birefringent (blue parallel with polarized light), rhomboid-shaped

Tackling Rheumatoid Arthritis (RA)

Erosions on x-ray. Erosions are areas on the bony surface of the joint that have been destroyed by chronic inflammation. They can be appreciated on x-ray appearing like small scoops taken out of the bone.

In early RA, x-ray of the hands and feet may be normal. One of the goals of treatment is to prevent erosions from occurring so early detection is paramount!

*Clinical Pearl: Remember an x-ray only shows the bony changes occurring in autoimmune diseases like RA. Synovial inflammation will not be visible on an x-ray image.