Présentations atypiques des maladies microcristallines

All three crystal-related rheumatic diseases are well known from physicians. They are clearly associated with typical anatomical sites, including enthesis and tendons for basic calcium phosphate crystals, joints and periarticular sites for gout and calcium pyrophosphate crystal deposit disease. However their location at the spine level or even at the sacroiliac joints might be difficult to diagnose. Destructive arthropathies related to these crystals can lead to differential diagnosis including septic arthritis or neuroarthropathy. In very rare cases, other unusual crystals such as crystal cryoglobulin, cholesterol, and phospholipid spherulites, can be difficult to identify.