Four separate and distinct manifestations of this disease exist, as follows: [Pseudogout] An acute presentation appears very similar to gout. The knee most often is affected. The shoulder, elbow, ankle, and familiar first metatarsophalangeal (MTP) joint frequently are involved as well. [Tophaceous pseudogout] The calcium pyrophosphate material can deposit in large accumulations, producing a pseudotumor. [Familial calcium pyrophosphate dihydrate deposition] A familial pattern which appears at a much earlier age, often as early as the third decade of life. It tends to be more aggressive, with a more ominous long-term prognosis. [Osteoarthritis] The most common presentation is that of osteoarthritis (OA) alone. Symptoms are identical to those of the typical patient with OA, with the exception that, at some point, the presence of calcium pyrophosphate crystals is appreciated. Most often, this is identified by the presence of chondrocalcinosis. Chondrocalcinosis increases in frequency with age. Injury and surgery may aggravate symptoms.