The World Health Organization (WHO) classifies MDS into three grades: low, intermediate, and high. The classification is primarily based on the type and degree of dysplasia, abnormal cytogenetic testing, the presence of ring sideroblasts, the percentage of blasts, and the presence or absence of Auer rods.
The classifications of MDS, according to WHO, include:
MDS with single lineage dysplasia: granulocytic, erythroid, or megakaryocytic
MDS with ring sideroblasts: the presence of 15% ring sideroblasts on the Prussian blue stained marrow smear
MDS with multilineage dysplasia: dysplasia in two, or the three myeloid lines
MDS with excess blasts (1&2) *refer to image on the right
MDS with isolated del(5q) chromosome