Pseudogout/CPPD

Calcium pyrophosphate (CPP) deposition (CPPD) can lead to acute inflammatory arthritis that can closely resemble a gout flare. CPPD can be asymptomatic, cause acute or chronic disease, and overlap with osteoarthritis.

CPPD typically affects older patients, and prior trauma to the joint is a risk factor. Increasing age leads to higher rates of chrondocalcinosis.

In younger patients, metabolic disease (hyperparathyroidism, hemochromatosis, hypophosphatasia, hypomagnesemia) can contribute.

The pathophysiology is poorly understood.

Clinical Manifestations and Diagnosis

Acute CPPD

Acute CPPD arthritis can present similarly to Gout. Flares are typically milder and less commonly affect the MTP joint, but can last for weeks or months. Definitive diagnosis requires identification of CPP crystals in synovial fluid (which are rhomboid shaped and positively birefringent). Joint infections can coexist.

The crowded dens syndrome is CPPD of the C2 atlantiaxial joint which can lead to severe neck pain, neck stiffness, fever, and headache which can mimic acute meningitis!

Chronic CPPD

Can manifest as chronic CPPD inflammatory arthritis which is a polyarthritis involving the wrists and MCP ("pseudo-RA") which is difficult to treat. Or, can present as OA-CPPD with typical OA findings involving joints not commonly associated with OA such as shoulders or MCP joints. CPP may play a causal role in the development of OA in these patients.

Management

There is no known mechanism for dissolving the CPP crystals or preventing their formation. Treatment aims to decrease the inflammatory manifestations of disease.

References

  1. MKSAP 19