Isochromosome 9q in acute lymphoblastic leukemia: a new non-random finding.

The presence of an isochromosome is commonly associated with late-stage disease and has rarely been reported at diagnosis in hematological malignancies. Five patients (two males and three females aged 3, 6, 13, 13, and 35 years) with an acquired i(9q) at diagnosis of acute lymphoblastic leukemia (ALL) are presented; in one case it was the sole karyotypic change. The patients presented in November or January, two in 1983/84, three in 1987/88. The latter were three of 100 unselected ALL cases referred over a three year period for cytogenetics and successfully karyotyped. Two had a prior history of pancytopenia. Features of high risk ALL in these patients included age over 10 years (three cases), leukocyte counts greater than 200 x 10(9)/liter (two cases) and pre-B immunological phenotype (two cases). All achieved remission on standard protocols. One patient is disease free over 4.5 years from diagnosis. One relapsed at 3.5 years and is well following a bone marrow transplant in second remission. Follow-up for the remaining three patients is between 9 and 11 months. Our findings indicate that i(9q) frequently with additional chromosome change is a feature of newly diagnosed ALL.