Clinical presentation of calcium pyrophosphate deposition
Acute calcium pyrophosphate crystal arthritis presents as an acutely inflamed joint, mimicking gout. The knee and the wrist are the most commonly affected sites (a point of difference from gout) but the disease may involve other joints and tendons. Acute attacks can be accompanied by fever and leucocytosis, mimicking septic arthritis.
A rare manifestation of acute calcium pyrophosphate crystal arthritis is the ‘crowned dens’ syndrome, which affects females more commonly than males. It presents as acute neck pain and stiffness, often accompanied by fever and elevated inflammatory markers. Typically, there is periodontoid ‘crown-like’ calcification above the dens. This can be observed on coronal views on cervical computed tomography (CT) scans, but is not typically visible on plain X-rays.
Acute calcium pyrophosphate crystal arthritis may also present as pseudoneuropathic joint disease, with severe destruction resembling a Charcot joint.
Chronic calcium pyrophosphate crystal inflammatory arthritis refers to the occasional presentation of chronic oligoarthritis or polyarthritis with inflammatory features, and superimposed flares. It may involve the knees, second and third metacarpophalangeal joints, wrists, shoulders, elbows, hips and midtarsal joints. Chronic calcium pyrophosphate crystal inflammatory arthritis should be considered in the differential diagnosis of rheumatoid arthritis in older adults.
Osteoarthritis with calcium pyrophosphate deposition may be distinguished from osteoarthritis without calcium pyrophosphate deposition by the presence of more osteophytes, the involvement of different joints, and more inflammatory features.