Megakaryoblastic disorders in children.

Acute leukemia is the most common neoplasm in children, of which approximately one fourth of cases are acute myeloid leukemia. To a large extent, the clinicopathologic spectrum of acute myeloid leukemia seen in the pediatric age group is similar to that in adults. However, megakaryoblastic proliferations, including transient myeloproliferative disorder and acute megakaryoblastic leukemia, occur exclusively or predominantly in children. Although the clinical and pathologic features of these disorders have been well characterized, until recently their pathogenetic mechanisms have remained poorly understood. Recent advances have provided important insight into the pathogenesis of these disorders, and they provide a molecular basis for a clinically meaningful classification of primary megakaryoblastic disorders in the pediatric age group.