Myelodysplastic/myeloproliferative disease with erythropoietic hyperplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24): first description of a case B Simone Heiss MD a , Martin Erdel PhD b , Eberhard Gunsilius MD c , David Nachbaur MD c , Alexandar Tzankov MD a, * a Institute of Pathology, Medical University of Innsbruck, 6020 Innsbruck, Austria b Department of Medical Genetics, Molecular and Clinical Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria c Department of Hematology and Oncology, Medical University of Innsbruck, 6020 Innsbruck, Austria Received 16 January 2005; accepted 21 July 2005 Summary 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. Immunohis- tochemically, 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. D 2005 Elsevier Inc. All rights reserved. 1. Introduction Myelodysplastic diseases/myeloproliferative diseases (MDS/MPD) are defined by the World Health Organization (WHO) classification of tumors of hematopoietic and 0046-8177/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.humpath.2005.07.020 B This study was supported by the Krebshilfe Tirol, Innsbruck, Austria. T Corresponding author. E-mail address: alexandar.tzankov@uibk.ac.at (A. Tzankov). Keywords: Myelodysplastic/ myeloproliferative diseases; Erythroleukemia; t(8;9) Human Pathology (2005) 36, 1148 – 1151 www.elsevier.com/locate/humpath