Calcium deposits under the skin of the knee of a Hispanic female patient with CREST syndrome. CREST is a form of scleroderma, a chronic, rheumatic autoimmune disease. It is an acronym for its five main features. Calcinosis - formation of calcium deposits in soft tissue; Raynaud's phenomenon - discolouration of the fingers and toes caused by decreased blood supply; Esophageal (oesophageal) motility disorder - difficulty in swallowing; Sclerodactyly - a localized thickening and tightness of the skin of the fingers or toes; Telangiectasias - small dilated blood vessels near the surface of the skin or mucous membranes. The condition has been related to previous Borrelia burgdorferi bacteria infections. There is no cure.