Crystalline Arthropathies

Question 1

What are the three main crystal types in crystalline arthropathies?

Answer 1

Basic calcium phosphate (BCP)

Calcium pyrophosphate dihydrate (CPPD)

Monosodium urate (gout)

Question 2

Where do basic calcium phosphate crystals deposit?

Answer 2

Soft tissues (acute calcific periarthritis), joints (BCP arthropathy), and tendons (calcific tendinitis)

Question 3

What is acute calcific periarthritis?

Answer 3

Deposition of BCP crystals in soft tissues leading to joint swelling, tenderness, warmth (similar to cellulitis, gout, pseudogout, septic arthritis, etc). Intense local inflammation wtih juxta-articular deposition of hydroxyapatite.

Question 4

Where are acute calcific periarthritis depositions most commonly located?

Answer 4

Shoulders, greater trochanters of hips, elbows, wrists, and digits. First MTP common in women

Question 5

What is BCP arthropathy?

Answer 5

Severe degenerative, destructive arthritis of the shoulder joint, leading to loss of rotator cuff (cannot abduct arm, huge swelling), BCP crystals in synovial fluid, and destructive changes on X-ray.

Question 6

Who is most commonly affected by BCP arthropathy?

Answer 6

Women > 70 years old

Question 7

What is Milwaukee Shoulder Syndrome?

Answer 7

BCP arthropathy of the shoulder joint

Question 8

What joints are most commonly affected by BCP arthropathy?

Answer 8

Shoulder, knees, hips, finger. Bilateral involvement common.

Question 9

What is calcific tendinitis?

Answer 9

BCP depositions in tendons, mostly in the shoulder, that causes frozen shoulder

Question 10

What muscles are affected by shoulder calcific tendinitis?

Answer 10

Rotator cuff: supraspinatus, infraspinatus, subscapularis

Question 11

What joints besides the shoulder can be affected by calcific tendinitis?

Answer 11

Hand, wrist, hip, knee, foot, and neck

Question 12

What is the microscopic appearance of BCP?

Answer 12

Shiny coins on LM, not birefringent on polarized light, can see individual crystals on EM (diagnostic)

Question 13

What are the treatments for BCP conditions?

Answer 13

NSAIDs, PT, intra-articular corticosteroid injections, surgery

Question 14

What are the ABCs of BCP arthropathy?

Answer 14

A: acute calcific periarthritis, alizarin red stain, atypical gout

B: BCP arthropathy, not birefringent

C: calcific tendinitis, cuff (supraspinatus), coins “shiny” on light microscopy

Question 15

What is calcium pyrophosphate dihydrate deposition disease?

Answer 15

A disease with CPPD deposits in cartilage that occur mostly in knees and wrists, and can be asymptomatic or symptomatic

Question 16

What do CPPD crystals look like?

Answer 16

Positively birefringent rhomboids under polarized light

Question 17

What is pseudogout?

Answer 17

A disease where CPPD crystals deposit in joint spaces, leading to fever, malaise, acute onset of joint pain, swelling, erythema/tenderness/warmth over joints that mostly affects large joints.

Question 18

How is pseudogout diagnosed?

Answer 18

Aspirate joint fluid to look for inflammatory fluid and crystals within PMNs

Question 19

What are the clinical associations of CPPD?

Answer 19

Advanced age (> 50)

Osteoarthritis

Long-term consequences of mechanical knee joint trauma

Associated with systemic metabolic disease

Question 20

What is the treatment for CPPD crystal deposition diseases?

Answer 20

NSAIDs, intraarticular steroid injections, IL-1 inhibitors, glucocorticoids

Question 21

How are attacks of CPPDs prevented?

Answer 21

They cannot be prevented, only treatment is for acute attacks after they happen

Question 22

What is the sex distribution of gout?

Answer 22

More men than women (3 or 4:1) until menopause (1:1 after) because estrogen breaks down the crystals

Question 23

What are gout risk factors?

Answer 23

• prevalence increases with age
• obesity
• diet rich in purines (meat, shellfish, beer, soda)
• thiazides, cyclosporins, low dose ASA
• renal insufficiency
• organ transplantation
• inborn errors of metabolism

Question 24

What is hyperuricemia?

Answer 24

Due to overproduction and under excretion of uric acid, treated to prevent acute flair-ups of gout.

Treatment goal < 6.0 mg/dL

Question 26

What are the treatments for uric acid underexcretors?

Answer 26

CANT LEAP

Cyclosporine

Alcohol

Nicotinic acid

Thiazide

Lasix

Ethambutol

Aspirin (low dose)

Pyrazinamide

Question 27

What condition can lead to uric acid overproduction?

Answer 27

Cancer (causes increased cell turnover)

Question 28

What are the four stages of gout?

Answer 28

Asymptomatic hyperuricemia

Acute gouty arthritis

Intercritical gout (asymptomatic intervals between acute attacks)

Chronic tophaceous gout (uric acid deposits in small tissues)

Question 29

How is gout diagnosed?

Answer 29

Aspiration of joint showing monosodium urate crystals that are negatively birefringent (yellow when parallel to polarizer, needle shaped)

Question 30

What disease is this?

Answer 30

Gout

Question 31

What is the acute treatment of gout?

Answer 31

generally goal = reduce body’s inflammatory attack on crystals

• Colchicine
• NSAIDs
• Steroid injection (especially for monoarticular)
• Initiate prophylactic agent like allopurinol (chronic uric acid lowering therapy)

Question 32

What are indications for chronic gout therapy?

Answer 32

• >2-3 gout attacks within 1-2 years
• Renal stones
• Tophaceous gout
• Erosions on xray

Question 33

What are gout recurrence prevention strategies?

Answer 33

• dietary changes (reduce meat, beer, extra frutose consumption)
• xanthine oxidase inhibitors (allopurinol)
• Uricosurics - prevent renal tubular resorption (probenicid)
• Uricases

Question 34

What kind of crystal is this?

Answer 34

BCP

Question 35

What kind of crystal is this?

Answer 35

CPPD