Myelodysplastic/myeloproliferative disease with erythropoietic hyperplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24): first description of a case.

We report on a patient fulfilling the diagnostic criteria of unclassifiable myelodysplastic/myeloproliferative diseases with prominent erythropoietic hyperplasia/dysplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24). The patient presented with B-symptoms, erythroblastemia, thrombopenia, marked eosinophilia, presence of myeloid precursors in the peripheral blood, and decreased erythropoietin level. Nodular peritrabecular polymorphous blasts, dysplastic megakaryocytes, and a diffuse argyrophilic fibrosis were detected in the trephine bone marrow biopsy. Immunohistochemically, the blasts stained positively for glycophorin C and hemoglobin A; the proliferation fraction was nearly 90% in the Ki-67 stain. Expression of the phosphorylated Janus kinase 2 was detected in almost all megakaryocytes and in isolated erythroblast islets, suggesting a probable activation of Janus kinase 2, the jak-2 gene being mapped on 9p24. Ten months after initial diagnosis, the disease progressed to frank acute erythroid leukemia. We report for the first time a myelodysplastic/myeloproliferative disease (erythroid preleukemia) accompanied by the specific chromosomal aberration t(8;9)(p23;p24), distinct histopathology, and clinical and laboratory symptoms, and progress to acute erythroid leukemia.