Hematopathological concepts and controversies in the diagnosis and classification of myelodysplastic syndromes.

Although the diagnosis and classification of most cases of the myelodysplastic syndromes (MDS) is usually accomplished without difficulty, a minority of cases may pose diagnostic problems. In many cases the diagnostic dilemma can be solved by adhering to basic guidelines recommended for evaluation of patients suspected of having MDS, and in particular to the quality of the blood and bone marrow specimens submitted for morphologic, immunophenotypic and genetic studies. In other cases, such as patients who have hypocellular MDS or MDS with fibrosis, the criteria for making a diagnosis may be difficult if not impossible to apply, and in still others the diagnostic uncertainty is because the minimal criteria necessary to establish the diagnosis of MDS are not always clearly stated. In this review, some of these diagnostic problems are addressed and some general guidelines for resolving them are suggested. In addition, data are presented that illustrate that the WHO classification offers a valuable tool in the diagnosis and classification of MDS.