[Importance of immunomorphometric evaluation of the size and number of megakaryocytes in normal and pathologic bone marrow].

The aim of the present study was to evaluate the significance of immunomorphometric assessment of megakaryocyte size and number in normal and pathologic human bone marrow. Thus, we compared morphometric characteristics of megakaryocytes in 56 bone marrow trephine biopsies stained by immunohistochemical and conventional techniques. Morphometric results showed that precise megakaryocyte size in normal and pathologic samples can be calculated even by using conventional staining technique, but only employing specific stereological corrections. Immunomorphometric evaluation revealed populations of "small" megakaryocytes (< 14 microns), "morphologically unrecognized" by conventional staining technique (promegakaryoblasts in normal and stimulated as well as micromegakaryocytes in pathologic bone marrow). In patients with normal and stimulated megakaryocytopoises percentage of "small" megakaryocytes was generally low (10.6% and 14%, respect.); so, megakaryocyte number was similar in immunohistochemically and conventionally stained sections. In contrast, percentages of "small" megakaryocytes were significantly higher in patients with stem cell disorders (namely, myelodisplastic syndrome and chronic granulocytic leukaemia), as compared to controls (35.3% in MDS; 22.9% in CML and 10.6% in controls). In those patients megakaryocyte numbers were more sensitively detected by immunohistochemistry than by conventional staining.