The bone marrow aspirate smear shows hypercellularity with a predominance of granulocytic proliferation that is similar to the peripheral blood. There is minimal dysplasia in the myeloid lineages (granulocytic, erythroid, or megakaryocytic). The percentage of blasts is less than 5% of the total bone marrow nucleated cells. If the blasts reach 10% or more, it indicates progression to the accelerated phase.
The bone marrow megakaryocytes are smaller than normal and are called “dwarf” megakaryocytes as seen in the image to the right. They may be normal in number or increased.
Pseudo-Gaucher cells, or sea-blue histiocytes, are macrophages commonly seen in CML and are derived from the neoplastic clone.
The bone marrow in the chronic phase may show moderate to increased reticulin fibrosis.
Pseudo-Gaucher cell
Sea-blue histiocyte
