CLINICOPATHOLOGICAL IMPACT OF THE INTERACTION BETWEEN MEGAKARYOCYTES AND MYELOID STROMA IN CHRONIC MYELOPROLIFERATIVE DISORDERS - A CONCISEUPDATE

In this report an attempt has been made to discuss some of the issues pertinent to myelofibrosis complicating chronic myeloproliferative dis orders (CMPDs) that are significantly associated with megakaryocyte fu nction. In this context, biochemical, clinical and particularly morpho logical features were reviewed. Morphological findings based on elabor ate techniques were in keeping with the assumption that in chronic mye loid leukemia (1) the number of CD61-positive megakaryocytes, and in p articular their precursors were the parameters most closely associated with myelofibrosis (2) an increased content of reticulin fibers in fo llow-up biopsies significantly correlated with laboratory data indicat ive of a high tumor burden (anemia, peripheral blasts, hepatosplenomeg aly) and thus a more advanced stage of the disease process (3) even a slight increase in reticulin, i.e. doubling of the normal fiber densit y was associated with a worse prognosis independent of therapeutic reg imens given (4) Dynamics of myelofibrosis was significantly influenced by treatment. In this context, calculation of the myelofibrosis progr ession index (MPI) revealed a higher score following interferon therap y compared with busulfan. In addition, in idiopathic myelofibrosis (5) the evolution of myelofibrosis was unpredictable and according to the MPI, progression occurred at a relatively low rate (6) proliferation and dilatation of sinusoids accompanying intravascular hematopoiesis a nd collagen type IV deposits were predominant features in later (fibro -osteosclerotic) stages in the course of disease (7) transmural migrat ion of megakaryocytes demonstrated by three dimensional reconstruction revealed a mole-like tunneling through the thickened sinusoidal wall. A very careful assessment of the numerous correlations between bone m arrow features and laboratory data will allow clinicians and pathologi sts to gain a better insight into the mutual relationships between hem atological and morphological findings in CMPDs.