Marrow cell uptake by megakaryocytes in routine bone marrow smears during blood loss

In studying smears of marrow aspirates, we have encountered the presence of normal appearing haemopoietic cells within megakaryocytes. We have then searched routine marrow smears from 125 patients seen in our service during 3 years. The presence of marrow cells (granulocytic, erythroid, and lymphoid cells) within megakaryocytes was seen in 16 cases of whom 9 had documented bleeding and 5 had carcinoma. 3 patients were suspected of bleeding but this was not documented. 56% of patients with bleeding and 83% of patients with carcinoma seen during this period displayed this pehnomenon. A search for this phenomenon in routine marrow smears may reveal unsuspected blood loss.