Periarticular calcific deposits mimicking acute arthritis.

Calcium salt deposition occurring outside joints must be distinguished from calcification due to pyrophosphate deposition within joint cartilage (chondrocalcinosis). Extra-articular deposits, localized to tendinous, capsular, and ligamentous tissue (Sandstrom, 1938), usually present as acute painful inflammation round the deposit, mimicking acute arthritis. Occasionally, they are discovered incidentally in a presymptomatic or mildly sypmtomatic phase.