The contribution of Auer rods to the classification and prognosis of myelodysplastic syndromes.

Auer rods were first recognized at the beginning of this century. Their presence soon became considered to be an unequivocal manifestation of a leukemic process. Possibly influenced by this long-held assumption, in 1982 the French-American-British co-operative group (FAB) incorporated the presence of Auer rods into a classification system of the myelodysplastic syndromes that remains in widespread clinical usage today. Although unsubstantiated at the time, the presence of Auer rods was suggested to indicate a rapidly progressive disorder and a poor prognosis. In the absence of studies confirming the utility of Auer rods as a diagnostic criterion, the FAB classification system of myelodysplastic syndromes has been widely used to allocate therapy. In this review we examine the early descriptions of Auer rods and critically evaluate the studies examining the value their presence has in the classification and prognosis of patients with myelodysplastic syndromes.