[Morphology: a critical phase in the diagnosis of myelodysplastic syndromes]

Diagnosis and classification of myelodysplastic syndromes (MDS) are based on the integration of morphology, immunophenotype, histology, genetics and molecular analysis. The role of cytomorphology in this context, however, remains fundamental and preliminary to the application of the other methods. The first modern classification of MDS, originally published by the FAB (French-American-British) Group in 1985, was based on the recognition of five different diagnostic categories. The more recent 2008 WHO classification of hematopoietic neoplasms has widened and modified the FAB approach, by including seven different cytomorphological entities and decreasing the threshold of the blast cell percentage to 19% for the discrimination of MDS from acute myeloid leukemias. In addition, chronic myelomonocytic leukemia is now included in the new group or MDS/myeloproliferative neoplasms. Finally, precise quantitative and qualitative criteria are provided, with the aim to improve microscope method standardization.