Detection of a t(1;22)(q23;q12) translocation leading to an EWSR1-PBX1 fusion gene in a myoepithelioma.
Chromosome banding as well as molecular cytogenetic methods are of great help in the diagnosis of mesenchymal tumors. Myoepithelial neoplasms of soft tissue including myoepitheliomas, mixed tumors, and parachordomas are diagnoses that have been increasingly recognized the last few years. It is still debated which neoplasms should be included in these morphologically heterogeneous entities, and the boundaries between them are not clear-cut. The pathogenetic mechanisms behind myoepithelial tumors are unknown. Only five parachordomas and one mixed tumor have previously been karyotyped, and nothing is known about their molecular genetic characteristics. We present a mesenchymal tumor classified as a myoepithelioma that had a balanced translocation t(1;22)(q23;q12) as the sole karyotypic change. A novel EWSR1-PBX1 fusion gene consisting of exons 1-8 of the 5'-end of EWSR1 and exons 5-9 of the 3'-end of PBX1 was shown to result from the translocation. Both genes are known to be targeted also by other neoplasia-specific translocations, PBX1 in acute lymphoblastic leukemia and EWSR1 in several solid tumors, most of which are malignant. Based on the structure of the novel fusion gene detected, its transforming mechanism is thought to be the same as for other fusion genes involving EWSR1 or PBX1.
Brandal
Petter
P
Department of Oncology, Division of Cancer Medicine and Radiotherapy, The Norwegian Radium Hospital, Rikshospitalet University Hospital, Montebello, Oslo, Norway. petter.brandal@klinmed.uio.no
Panagopoulos
Ioannis
I
Bjerkehagen
Bodil
B
Gorunova
Ludmila
L
Skjeldal
Sigmund
S
Micci
Francesca
F
Heim
Sverre
S
D002148:Calmodulin-Binding Proteins / Q000235:genetics*; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008875:Middle Aged; D009208:Myoepithelioma / Q000235:genetics* / Q000473:pathology; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D016133:Polymerase Chain Reaction; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics*; D014178:Translocation, Genetic / Q000235:genetics*
D002148:Calmodulin-Binding Proteins; D004268:DNA-Binding Proteins; C500986:EWSR1 protein, human; D015514:Oncogene Proteins, Fusion; D000075062:Pre-B-Cell Leukemia Transcription Factor 1; D011518:Proto-Oncogene Proteins; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins; C083400:PBX1 protein, human