Evidence from molecular genetic and cytogenetic analyses that bone marrow histopathology is reliable in the diagnosis of chronic myeloproliferative disorders

The histopathology of chronic myeloproliferative diseases

This chapter discusses the histopathology of five groups of chronic myeloproliferative diseases: chronic myeloid leukaemia, polycythaemia vera, essential thrombocythaemia, chronic idiopathic myelofibrosis and unclassifiable myeloproliferation. Histological staging of the four haematologically defined diseases is performed by grading the three most prominent variables: megakaryocytes, fibres and blasts. Histological outcome is correlated to the staging of diagnostic bone marrow biopsies; megakaryocytic involvement is correlated with the risk of myelofibrosis. An excess of blasts is related to the risk of leukaemic transformation. The progression of myelofibrosis depends on the grade of fibre increase at diagnosis. These three statements are highly significant and valid for all types of chronic myeloproliferative disorders. The results of cytogenetics are discussed in relation to the histological classification for these patient groups. Changes in bone marrow histology following myelosuppressive therapy is presented. Prospective studies under standardized protocol therapy are recommended, so that the long-term effects of therapy can be assessed.

Classification and staging of Ph-negative myeloproliferative disorders by histopathology from bone marrow biopsies

The present study illustrates characteristic features of histopathology in the 3 non-leukemic, Ph-negative groups of chronic myeloproliferative diseases (CMPD). Attention is paid to the final outcome of CMPD, especially its transformation into acute leukemias and the occurrence of myelofibrosis from bone marrow biopsies (BMB) in a total of 1,716 CMPD patients. Essential thrombocythemia (ET), polycythemia vera (P. vera), and chronic megakaryocytic granulocytic myelosis (CMGM) can readily be distinguished by histopathology from BMB in the great majority of patients without regarding laboratory data, leaving a compartment of about 12% unclassifiable cases. Histologic patterns of staging are the increase in number and pleomorphism of megakaryocytes (MK), increase in number and density of reticulin fibers and collagen fibrosis, and excess of blasts. These 3 criteria are each graded from 0 to 3 in every biopsy. From these, a staging results by means of the histology of BMB in each of the Ph-negative CMPD. This staging provides a classification by defined criteria which permits comparative studies, the possibility of monitoring the individual patients by follow-up histology, and offers a baseline for reliable evaluation of results from therapy protocols.