Masked Philadelphia chromosome due to the translocation (1q-;22q +) and small chromosome 19 in a case of acute leukemia.

The case of a 51-year-old female with acute myelomonocytic leukemia (AMMoL) and masked Philadelphia (Ph1) chromosome is reported. The Ph1 resulted from a translocation involving chromosomes 1 and 22, in which a segment of the long arm of one chromosome 1 (1q12----q25) was translocated to the long arm of one chromosome 22 at band 22q11. Additionally, a marker chromosome of unknown origin and deletion of the long arm of one chromosome 19 at band 19q12 were found. The literature on masked Ph1 chromosomes and changes of chromosomes 1 and 19 is briefly summarized.