Calcium pyrophosphate deposition disease (CPDD) is a metabolic disease resulting from the deposition of calcium pyrophosphate dihydrate (CPPD) in the joints. According to McCarty, five different clinical presentations can be seen; pseudogout is the one of them.

Pseudogout literally means "false gout". Occasionally it can be coexist with gout. It is most common in older people. The cause of pseudogout and CPPD deposits is unknown although can be precipitated by surgery or trauma or some diseases such as rheumatoid arthritis, myocardial infarction, heart failure.

Clinical manifestations of pseudogout are characterized by acute monoarticular or oligoarticular arthritis with pain and swelling usually in the knee or the wrist but gout typically affects joints of the toes and feet. Polyarticular attacks may occur on occasion.

The diagnosis of pseudogout is made by aspiration of the fluid from affected joints during an acute attack. The fluid examination by polarizing microscope is composed largely of calcium whereas gout crystals are made of uric acid. However, occasionally pseudogout could be coexisted with gout, so the two types of crystals can be found in the same joint fluid. A Gram stain of the fluid should be done to exclude septic arthritis.

Pseudogout may be treated be different methods depending on the attack. Fluid aspiration from the joint can reduce the pain and decrease the inflammation. Local ice applications and resting can help. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can be taken orally for moderate pain.

Long-term prevention of recurrent pseudogout could be done with small daily doses of colchicines.