Clonal evolution of marker chromosomes in a case of myelofibrosis with myeloid metaplasia and myeloblastic transformation.

The diverse spectrum of acquired chromosome abnormalities in a female patient with myelofibrosis and myeloid metaplasia is described. A sequence of karyotypic evolution involving a ring chromosome is postulated. The terminal clinical picture was unusual in that there was obstructive renal failure from extramedullary myeloblastic transformation and infiltration of the bladder, and this was also present in other sites. Initially neutrophils showed low alkaline phosphatases activity but latterly two distinct populations in which cells had either high activity or none.