Ph1-positive polycythemia vera

The rare presence of the ph1 chromosome in chronic myeloproliferative disorders other than chronic granulocytic leukemia (CGL), i.e. polycythemia vera (PV), myeloid metaplasia with myelofibrosis (MMM) and hemorrhagic thrombocytopenia (HT) raised the question whether or not the Ph1 chromosome is peculiar to CGL. In an attempt to answer this question, the authors reports six cases of positive-Ph1 of which two are from their personal experience and four from the literature. Three of these six cases converted to CGL. The authors conclude that the cases of Ph1-positive PV and HT are transition forms to CGL, and the cases of Ph1-positive MMM are in fact secondary forms derived from CGL.