Clinicopathological study of 9 cases of megakaryocytes in pleural and peritoneal fluids.

To systemically analyze megakaryocytes in pleural and peritoneal fluids and their clinical significance. We retrospectively examined 10,846 pleural, peritoneal, and pericardial fluid samples obtained from 3 hospitals over a 20-year period. Megakaryocytes were observed in the pleural fluid samples from 7 patients and peritoneal fluid samples from 2 patients, and the incidence was 0.83%. The clinical diagnoses of these 9 patients included myeloproliferative disorders, trauma, and tumors. The serous effusions in all 9 patients were bloody, and the megakaryocytes could be associated with trauma, bone marrow pollution, extramedullary hematopoiesis, or cancer. Additionally, differentiating between megakaryocytes and tumor cells or nuclear mesothelial cells in the pleural fluid is difficult. Therefore, megakaryocytes should be carefully observed and differentiated in pleural and peritoneal fluids because they can be confused with other cells in the clinic. Altogether, the megakaryocytes in the pleural and peritoneal fluids were mainly associated with contamination in the bone marrow or extramedullary hematopoiesis.