Pseudogout is a form of arthritis characterized by deposits of calcium pyrophosphate dihydrate (CPPD) crystals in a joint. Patients experience painful arthritic attacks in their joints, usually in the knee.

Pseudogout, also known as chondrocalcinosis or CPPD disease, is most common in older people. The exact cause of pseudogout and CPPD deposits is unknown. CPPD deposits may be linked to other disorders, such as rheumatoid arthritis. Heredity and joint trauma may also play a role in the development of pseudogout.

Gout and pseudogout have similar symptoms and are often confused with one another. The two main differences are the chemical compositions of crystal deposits and the areas of the body affected. Crystal deposits associated with pseudogout are composed largely of calcium, whereas gout crystals are made of uric acid. Furthermore, pseudogout is most common in the knees, but gout typically affects joints of the toes and feet.

A person with pseudogout may also have gout or another related disease. This often complicates diagnosis. Furthermore, some people may have large deposits of CPPD in certain joints and never experience the painful symptoms of pseudogout. Because of the possibility for overlap, a physician may also consider other causes of joint trouble, even when pseudogout has been diagnosed.

Pseudogout may be treated a number of ways depending upon the painfulness of attack. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can be taken orally for moderate pain.