Calcium pyrophosphate crystal deposition disease and other crystal deposition diseases.

"Tumoral" calcium pyrophosphate dihydrate (CPPD) crystal deposition in the ligamentum flavum is rare and can lead to compression myeloradiculopathy in the cervical spine and to spinal canal stenosis in the lumbar spine. CPPD crystal deposition disease is rarely associated with Bartter's syndrome and hypomagnesemia. Intramuscular corticotropin has proved effective in the treatment of acute episodes of pyrophosphate arthritis in patients with multiple medical illnesses in whom nonsteroidal anti-inflammatory drugs are contraindicated. IgG binding to CPPD crystals enhances neutrophil activation (by increasing intracellular cytoplasmic calcium levels) and seems to play a greater role in pyrophosphate than in urate crystal-induced inflammation. Transforming growth factor-beta 1 stimulates intracellular pyrophosphate generation by articular chondrocytes. The effect is inhibited by probenecid, an anion transport blocker, through interfering with the active transport of intracellular pyrophosphate to cartilage matrix where crystals form. Calcific tendinitis associated with underlying cortical bone erosions is an uncommon manifestation of apatite crystal deposition disease. Closed-needle tidal irrigation proved beneficial in two patients with Milwaukee shoulder syndrome. Two patients with nodular subcutaneous cholesterol crystal deposition are described.