Chromosomes and causation of human cancer and leukemia. XXXII. Unusual features of Ph1-positive acute myeloblastic leukemia (AML), including a review of the literature.

Five cases of Ph1-positive AML were studied. In all cases a Ph1-chromosome was shown with banding techniques to be due to a translocation between chromosomes No. 9 and No. 22. Cases 1 and 4 were found to have more than one Ph1 with evidence of only on Ph1-translocation accompanying other chromosome abnormalities. Two cases represented an unusual pattern of appearance and disappearance of the Ph1-positive clone during their clinical courses: Case No. 2 was originally Ph1-positive (46,XY,Ph1) but two months before his expiration the Ph1-positive clone was completely replaced by a newly developed Ph1-negative clone with an abnormal chromosome No. 21 (46,XY,21q+), whereas case No. 3, primarily Ph1-negative, developed a Ph1-positive clone among the previously karyotypically normal cells one month before death. The Ph1-positive AML cases presented have been discussed in relation to: 1) the genesis and significance of the Ph1-positive clone, 2) differentiation from the blastic phase of CML and 31 the general experience with Ph1-positive acute non-lymphocytic leukemia (ANLL), the world literature of which have been tabulated.