CD34 and acquired polycythemia vera: A bone marrow biopsy showed mildly increased total cellularity (55%), increased numbers of megakaryocytes, no significant increase in erythropoiesis or granulopoiesis, normal maturing granulopoiesis, no dysplasia, no increase in CD34-positive cells, and fibrosis grade 1 interpreted as spent phase polycythemia vera.