Cytogenetic and ultrastructural studies on ten patients with acute promyelocytic leukemia, including one case with a complex translocation.

Chromosomal banding analyses and ultrastructural studies were performed on ten cases of acute promyelocytic leukemia (APL-M3). A reciprocal translocation, t(15q + ;17q-), was found in six of them, and the possible breakpoints of these chromosomes were assigned at bands 15q22 and 17q12. In addition, trisomy 8, trisomy 8 and 21, and an isochromosome of the long arm of the translocated #17, i(17q-), were observed in addition to the 15;17 translocation in three cases, respectively. Furthermore, one patient was found to have a complex translocation in the marrow cells, i.e., 47,XX,+X,t(1p+;5q-;15q+;17q-). Ultrastructural studies demonstrated that the leukemic cells obtained from six of the seven patients with the chromosomal changes involving 17q12 and from two of the three with normal karyotypes contained stellate rough surface endoplasmic reticulum (stellate rER) complexes and/or inclusion bodies in part of the dilated rER.