The diagnostic and prognostic value of bone marrow immunostaining in myelodysplastic syndromes

Immunohistochemistry has been introduced as a means of increasing the diagnostic accuracy of bone marrow biopsy (BMB) in myelodysplastic syndromes (MDS); more recently the possibility of coupling immunostaining with other investigational techniques has broadened the spectrum of applications to the biology and physiopathology of MDS. Using panels of monoclonal antibodies (MoAbs), various histological classifications of MDS have been proposed as an alternative to the FAB criteria. The use of lineage-specific MoAbs has allowed a deeper insight into the dysplastic features of early hematopoietic precursors. The study of various gene products involved in the regulation of cell growth, proliferation and sensitivity to antineoplastic drugs, has revealed significant differences between MDS and morphologically-related disorders, particularly acute myelogenous leukemias (AML); these can be considered markers of a biological difference between the two groups of disorders and deserve consideration when designing therapeutic strategies for MDS. Both an increase in the percentage of cell positivity for the CD34 glycoprotein and a tendency of positive cells towards forming aggregates have been shown to be reliable predictors of leukemic transformation and survival, irrespective of the FAB subtype; furthermore, CD34 positivity has also proved to be a better prognostic factor than the presence of the abnormal localization of immature precursors (ALIP) on BMB. Finally, the simultaneous occurrence of "large" and CD34 positive aggregates can be proposed as a means of recognizing MDS patients with an exceedingly unfavourable prognosis, and who are therefore suitable for early aggressive therapy.