Crystalline Arthritis (Calcium Hydroxyapatite Deposition Disease) Flashcards
What are some causes of increased Hydroxyapatite (HA) deposition?
- Tissue Damage (dystrophic calcification)
- Hyperphosphatemia (Chronic Renal Failure -secondary Hyperparathyroid)
- Direct release from bone (Chonic stable OA, Milwaukee shoulder)
What is shown here?
• what would happen if you drew fluid?
Swollen/Convex right shoulder due to subacromial bursitis.
Cause - Hyperphosphatemia due to chronic renal failure
•If you took fluid from this bursa you would get fluid that appears as shown below
What is shown here?
• what has caused it?
Calcific Deposits in the Subacromial Bursa surrounding the right shoulder joint
**Also note the resorption of the distal clavical due to secondary hyperparathyroidism (probably due to chronic kidney failure that has impinged on the excretion of phosphate. Calcium phosphate being insolube deposits and you have low Ca2+ levels that lead to release of PTH from the parathyroids)
What do Calcium Phosphate crystals look like on microscopy?
Crystals that are roundish in appearance and will demonstate edge birfringence under polarized light. These crystals are generally NOT considered to be birfringent
What do you do to treat Hydroxyappetite Crystal Deposition?
NSAIDs or selective COX-2 inhibitors
Local Corticosteriod Injection
Local Irrigation
High-frequency therapeutic ultrasound to degrade BCP
Crystal Deposits
Do you expect you patient with Hydroxyapatite to present with an acute synovitis?
• what would you expect the synovial cell count to look like?
NO, synovitis is typically not ACUTE in these patients (WBCs typically less than 1000 cell/ul). This is a contrast with Gout and Pseudogout that typically involves WBCs 10,000-70,000 in the synovial fluid during acute attacks.
Where does ACUTE inflammation as a result of HA deposition typically occur?
• what diseases might this mimic?
Bursa are involved in Acute events.
• Subacromial Bursa may be affected (this might resemble something like polymyalgia rheumatica)
• Pseudopodagra has been described in young women with deposits in the bursae, tendons, ligaments, and soft tissue
***If you see a podgra-like syndrome taking place in a premenopausal woman then you should consider this**
How might the pattern of Hydroxyapatite deposition disease differ in patients on dialysis?
Patients with severe renal disease may develop SYMPTOMATIC articular and periarticular HA crystal deposition. This may be destrcutive and even involve the AXIAL SKELETON.
What are the central mechanisms in the pathogenesis of CPPD?
• Dyregulated Chondrocyte differentiation to hypertrophy and inorganic pyrophosphate (PPi) metabolism
What gene is linked to CPPD, what does it do?
• HOW IS IT INHERITED?
ANKH is inherited in an AUTOSOMAL DOMINANT fashion. ANKH codes for a PPi transporter.
What drives the inflammatory response in CPPD?
CPP crystals in CPPD activate NLRP3 (cryopyrin) inflammasome that in turn activates caspase-1 and IL-1ß processing and secretion that drive cell responses to CPP cystals.
What joints are affected by CPPD that are not affected by PRIMARY OA?
- MCP joints
- Wrist
- Elbow
You have a patient that is 45 and presents with wrist pain and aspiration of the joint shows weakly birefringent rhomboid crystals.
• Likely diagnosis?
• How should you work this up?
• what other phyisical finding would tip you off to a similar workup?
Dx: Pathologic finding are pathonomonic for CPPD
Workup: In patients under 55 with CPPD you should work this up by looking for additional causes like primary familial disorders and hyperparathyroidism. You should do this ESPECIALLY if the disease is polyarticular.
If you strongly suspect CPPD but the radiograph is negative, what should you do next?
• If you stongly suspect it then High-resolution ultrasound can be good for detection
What disease is HA crystal deposition disease intimately linked to?
• how does this differ from CPPD?
HA deposition disease and OA are intimately linked while there is no link between OA and CPPD.
