Isoderivative of deleted chromosome 20 in primary myelofibrosis (PMF) characterized by molecular cytogenetics and array CGH

Dear Editor, Primary myelofibrosis (PMF) is a BCR-ABL-negative chronic myeloproliferative disorder. Chromosomal abnormalities are heterogeneous but deletion of the long arm of chromosome 20 (del(20q)) is a recurrent abnormality observed in 20–30% in PMF [1]. A variant of deletion 20q, an isochromosome of the long arm of chromosome 20 with loss of interstitial material (ider(20q)), has recently been described in myeloid hemopathy [2–6]. To our knowledge, a sole case of primary myelofibrosis with ider(20q) has been published [7]. Here, we report two further cases. Patient 1 is a 79-year-old-woman who presented with chronic leukoneutropenia. Physical examination revealed neither hepatosplenomegaly nor lymphadenopathy. Trephine biopsy sections showed reticulin and collagen fibrosis with decreased cellularity. In fibrous tissue, megakaryocytes were dysplastic; granulocytic and erythroid lineages were nonexistent. An abdominal ultrasonography revealed a splenomegaly of 15.5 cm. JAK2 mutation was present. A diagnosis of primary myelofibrosis was made. Six months later, no sign of clinical evolution was observed. During these 6 months, the patient benefited from clinical surveillance, with blood parameters remaining stable. Hepatosplenomegaly was found at physical examination of a 71 year-old-woman (patient 2). The bone marrow aspirate revealed reticulin fibrosis. The patient received Ann Hematol (2009) 88:1157–1159 DOI 10.1007/s00277-009-0753-3