Musculoskeletal ImagingHyperlipoproteinaemia
a group of heritable disorders associated with increased plasma concentrations of cholesterol or triglycerides. The hyperlipoproteinaemias are divided into five types according to the predominant plasma lipoprotein pattern. Among the manifestations of these disorders are gout, arthralgias, arthritis and xanthomatous collections in soft tissue, tendons and subperiosteal and intraosseous locations.
Primary type I hyperlipoproteinaemia results from a hereditary abnormality in chylomicron removal. This form may occur as a secondary defect in diabetes mellitus, pancreatitis and alcoholism. Clinical features include lipaemia retinalis, hepatosplenomegaly, abdominal pain and pancreatitis.
Type II hyperlipoproteinaemia is related to an increase in the plasma concentration of low density lipoproteins or beta-lipoproteins. This type may be a primary autosomal dominant hereditary abnormality but may also occur secondary to hypothyroidism, plasma cell myeloma, macroglobulinaemia and obstructive liver disease. Findings include xanthomas and premature coronary, cerebral, and peripheral vascular disease.
Type III hyperlipoproteinaemia, or broad-beta disease, is associated with beta- or prebeta-lipoprotein abnormality. As a primary disorder, type III may be inherited as an autosomal recessive disorder; in rare instances it may occur secondary to severe insulinopenic diabetes and hypothyroidism. Xanthomas and premature peripheral vascular disease are apparent in patients with this disease.
Type IV hyperlipoproteinaemia is characterized by the presence of increased low density lipoproteins or prebeta-lipoproteins without chylomicronaemia. In its primary form, the disease appears to be an autosomal recessive disorder. Type IV hyperlipoproteinaemia may also occur secondary to diabetes mellitus, pancreatitis, alcoholism, hypothyroidism, glycogen storage disease, Gaucher's disease, gout and hypercalcaemia. Is manifestations include xanthomas, hyperuricaemia and coronary vascular disease.
Type V hyperlipoproteinaemia, which is similar to type IV, is probably an autosomal dominant hereditary disease. In this form, xanthomas, hyperuricaemia, abdominal pain, hepatosplenomegaly, paresthesias and lipaemia retinalis can be detected.
Xanthomas of various types are a prominent feature of hyperlipoproteinaemia. These xanthomas may be eruptive, tendinous, tuberous, or subperiosteal and osseous. They may be diagnosed using ultrasonography, CT and MR imaging. On MR images, the signal intensity of xanthomas varies, revealing persistent low to intermediate signal intensity on T1-weighted and T2-weighted spin-echo MR images and signal inhomogeneity. On occasion, however, focal areas of high signal intensity may be encountered on T2-weighted images.
In type II, a migratory polyarthritis may be detected affecting peripheral joints, and arthralgias may occur in patients with type IV hyperlipoproteinaemia.
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