Table 4.

Morphological criteria for severe aplastic anemia and myelodysplastic syndromes, type refractory cytopenia of childhood (EWOG-MDS 2008) (13, 82, 113).

	Myelodysplastic syndrome, type refractory cytopenia of childhood (MDS-RCC)	Severe aplastic anemia (SAA)
Erythropoiesis	Patchy distribution, increased numbers of proerythroblasts (left shift), increased numbers of mitoses	Lacking or single small focus with <10 cells, full maturation
Granulopoiesis	Marked decrease, left shift	Lacking or marked decrease, very few small foci with maturation
Megakaryopoiesis	Marked decrease or absence Micromegakaryocytes (to be detected by immunohistochemistry)	Lacking or very few, no micromegakaryocytes or other dysplastic megakaryocytes
Lymphocytes	Lymphocytes and plasma cells might be increased	May be increased focally or dispersed
CD34+ cells	No increase	No increase
Others	Mast cells might be increased Adipocytic bone marrow No increase in reticulin fibers (difference to adult MDS patients)	After initation of immunosuppressive therapy: similar to MDS-RCC