Cytogenetic Evidence for Splenic Origin of Blastic Transformation in Chronic Myeloid Leukaemia

Serial chromosomal analyses of bone marrow and spleen cells using the Giemsa banding technique were performed in a patient with chronic myeloid leukaemia followed from the chronic phase until blastic transformation. The results suggest that the spleen may be more important than the bone marrow for the further karyotypic evolution of Ph1‐positive cells which herald the blastic transformation.