Sitosterolemia is a rare autosomal recessive sterol storage disease characterized by the accumulation of phytosterols in the blood and tissues. Clinical manifestations include xanthomas, arthralgia and premature atherosclerosis. Hematological manifestations include hemolytic anemia with stomatocytosis and macrothrombocytopenia. The disease is caused by homozygous or compound heterozygous mutations in <i>ABCG5<i> (2p21) and <i>ABCG8</i> (2p21) genes.

Giant platelets are larger than 7 micrometers and usually 10 to 20 micrometers. The term giant platelet is used when the platelet is larger than the size of the average red cell in the field. (Description adapted from College of American Pathologists, Hematology Manual, 1998).