1. ¹Department of Pathology, UMass Memorial Medical Center, University of Massachusetts, Worcester, MA, USA
2. ²Department of Hematopathology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
3. ³Department of Pathology, Wilford Hall Medical Center, Lackland AFB, San Antonio, TX, USA
4. ⁴Myelodysplastic Syndrome Program, St. Vincent's Comprehensive Cancer Center, New York, NY, USA
5. ⁵Department of Pathology, Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA

Correspondence: Dr SA Wang, MD, Department of Hematopathology, 1515 Holcombe Boulevard, Unit 72, Houston, Texas 77030-4009, USA. E-mail: swang5@mdanderson.org

Received 10 March 2008; Revised 15 May 2008; Accepted 12 June 2008; Published online 12 September 2008.

Abstract

In the FAB (French–American–British) and WHO (World Heath Organization) classifications, the blasts in erythroleukemia (M6a) are enumerated from the marrow nonerythroid rather than the total-nucleated cells. However, the method for blast calculation in erythroid-predominant myelodysplastic syndrome (erythroblasts50%) is not specified either in the FAB or WHO classifications. We retrieved the files of 74 erythroid-predominant myelodysplastic syndrome patients (17% of all myelodysplastic syndrome) and 192 myelodysplastic syndrome controls (erythroblasts<50%). In erythroid-predominant myelodysplastic syndrome, by enumerating blasts from marrow nonerythroid cells rather than from total nucleated cells, 41 of 74 (55%) cases would be upgraded, either by disease subcategory or International Prognostic Scoring System. Importantly, the patients with <5% blasts demonstrated a superior survival to patients with 5% blasts (P=0.002); this distinction was lost when blasts were calculated from total-nucleated cells. Of cases with 5% blasts, cytogenetics rather than blast count correlated with survival. We conclude that in erythroid-predominant myelodysplastic syndrome, blast calculation as a proportion of marrow nonerythroid rather than total nucleated cells can better stratify patients into prognostically relevant groups.