The classification of MDS: from FAB to WHO and beyond

The purpose of any classification of hematologic neoplasms is to provide reliable criteria for their diagnosis and their classification into clinically relevant disease entities. In 1982, the French - American - British (FAB) group introduced such a classification for the myelodysplastic syndromes (MDS), a heterogenous group of diseases that prior to the FAB scheme was often referred to only as "preleukemia." Over the ensuing two decades, the FAB classification facilitated hundreds of morphologic, clinical, and genetic studies that helped to clarify the disease process and its management. The World Health Organization (WHO) classification of MDS is a consensus classification first introduced in 2001 and revised in 2008. It maintains much of the structure and philosophy of the FAB classification, but draws upon more recently acquired biologic and clinical information to refine the diagnostic criteria and improve its prognostic value. This paper outlines the evolution from the FAB to the WHO classification of MDS and gives a glimpse of what might lie beyond.