Unusual translocation and chronic myelocytic leukemia: "masked" Philadelphia chromosome (Ph 1)

An unusual Ph 1 translocation in a woman, 65 years old, with chronic myelocytic leukemia is reported. Cytogenetic analysis performed on 150 mitoses examined with Q-, R-, and C-banding revealed evidence for an unusual translocation involving the insertion of a segment of chromosome #9 into chromosome #22, thus masking the presence of a Ph 1. The anomaly can best be described as 46, XX, ins(22;9) (q11;q22 to 34).