Hyperlipidemias, lipid storage disorders, metal storage disorders, and ochronosis.
This review presents up-to-date information on many unusual causes of musculoskeletal disorders. These disorders are grouped together because in each there is abnormal accumulation of normal materials or accumulation of abnormal materials in cells or interstitial tissues. Most of these conditions or their associated musculoskeletal manifestations are rare. However, they may present to the adult or pediatric rheumatologist for diagnosis or therapy or both. Gout, because of its prevalence, has been excluded from this review, but it is included briefly in the discussion of the specific arthritides associated with hyperlipidemias. Disorders associated with abnormal lipid storage in which bone and joint pathology occur frequently include Gaucher's disease, histiocytosis-X, and multicentric reticulohistiocytosis. The rarer disorders of this type discussed are Fabry's disease, sea-blue histiocytosis, and Farber's disease. The abnormal accumulation of metal ions in hemochromatosis and in Wilson's disease are probably causative, either directly or indirectly, in the musculoskeletal features of these diseases, while in ochronosis, calcium crystal deposition accompanies the cartilage degradation characteristic of this disease.