Acquired hypomegakaryocytic thrombocytopenic purpura. Occurrence in a patient with absent thrombopoietic stimulating factor.

A 49-year-old woman had purpura and thrombocytopenia not associated with drugs or identifiable underlying disease. The platelet survival was normal and the marrow showed a sharp reduction in megakaryocytes with preservation of other cell lines. There was no response to steroids or infusion of fresh frozen plasma. Lithium carbonate therapy similarly had no effect. Thrombopoietic activity was absent in serum and urine samples. Erythropoietin activity was normal. In vitro formation of granulocyte-macrophage colonies in soft agar was normal. The case represents a unique incidence of selective megakaryocytic hypoplasia, though to result from a failure in stem cell differentiation.