5q-syndrome presenting chronic myeloproliferative disorders-like manifestation: A case report

A 28-year-old Japanese woman with suspected essential thrombocythemia (ET) had marked thrombocytosis, mild leukocytosis with normal neutrophil alkalin e phosphatase activity, and no anemia. She was monitored without being give n any medication. Eleven years later, complete blood counts showed no remar kable changes but some nonlobulated mononuclear megakaryocytes were found i n the bone marrow. Cytogenetic analysis revealed deletion of the long arm o f chromosome 5 (5q-), Subsequently, hemoglobin and platelet counts decrease d gradually, splenomegaly appeared and progressed, after which myelofibrosi s developed. Acute leukemia developed 16 years after the first documentatio n of thrombocytosis, 5q- syndrome is known to be a myelodysplastic syndrome (MDS) with unique clinical features and cases with this syndrome presentin g with thrombocytosis of more than 1,000 x 10(9)/L but without anemia are r are. Furthermore, It is noteworthy that in this patient transition to acute leukemia occurred following development of myelofibrosis and marked spleno megaly, which are generally observed in blastic crises resulting from chron ic myeloproliferative disorders (CMPD). The patient showed features Indicat ive of CMPD rather than of MDS in spite of presenting with 5q- chromosomal abnormality. This case supports the concept of "mixed myelodysplastic and m yeloproliferative syndromes" and suggests the possibility of the appearance of CMPD-like manifestations in 5q- syndrome. Am. J, Hematol, 64:120-123 20 00, (C) 2000 Wiley-Liss, Inc.