Radiological identification and analysis of soft tissue musculoskeletal calcifications.

Musculoskeletal calcifications are frequent on radiographs and sometimes problematic. The goal of this article is to help radiologists to make the correct diagnosis when faced with an extraosseous musculoskeletal calcification. One should first differentiate a calcification from an ossification or a foreign body and then locate the calcification correctly. Each location has a specific short differential diagnosis, with minimal further investigation necessary. Intra-tendon calcifications are most frequently associated with hydroxyapatite deposition disease (HADD). In most cases, intra-articular calcifications are caused by calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. Soft tissue calcification can be caused by secondary tumoural calcinosis from renal insufficiency, or collagen vascular diseases and by vascular calcifications, either arterial or venous (phlebolith). TEACHING POINTS: • Calcifications have to be differentiated form ossification and foreign body. • A musculoskeletal MRI study must always be correlated with a radiograph. • The clinical manifestations of calcifications may sometimes mimic septic arthritis or sarcoma. • HADD and CPPD crystal deposition have a distinct appearance on radiograph. • Calcinosis is more frequently caused by chronic renal failure and scleroderma.