Pure erythroid leukemia and erythroblastic sarcoma evolving from chronic myeloid neoplasms

Objectives: Pure erythroid leukemia (PEL) is an extremely rare entity that may, even more rarely, evolve from a preexisting chronic myeloid neoplasm (CMN); there is minimal literature regarding this latter phenomenon. Methods: We describe 14 patients with PEL that represented progression from a preexisting myelodysplastic syndrome (MDS, n=8) or myeloproliferative neoplasm (MPN, n=6), three of which manifested as erythroblastic sarcoma (EBS), a rare entity. These patients had a highly complex karyotype with prominent clonal evolution and a very aggressive clinical course. Results: Patients with PEL from MDS showed a more rapid progression time to PEL and had lower platelet counts compared with PEL from MPN. No other significant differences were found between the two groups. Conclusions: These data represent the largest cohort of patients with PEL and an antecedent CMN, as well as the largest series of EBS reported to date, and underscore the unique morphologic, cytogenetic, immunophenotypic, and clinical features of this uncommon entity.