A malignant myeloproliferative disorder occurred in a Japanese child with Down's syndrome. In addition to the features of acute myeloblastic leukemia, the patient demonstrated extensive megakaryocytic infiltrates in spleen, liver, lymph nodes, kidneys, and pancreas. The disturbance of bone marrow function in Down's anomaly may involve thrombopoiesis as well as granulopoiesis.
Okada H, Liu PI, Hoshino T, Yamamoto T, Yamaoka H, Murakami M. Down's Syndrome Associated With a Myeloproliferative Disorder. Am J Dis Child. 1972;124(1):107-110. doi:10.1001/archpedi.1972.02110130109018