Rearrangement of the EWSR1 gene is now known to occur in up to half of all skin and soft tissue myoepithelial tumors, with a wide family of documented fusion partners.
Considering the unusual location, we additionally performed a cytogenetic analysis to confirm the presence of the EWSR1 gene rearrangement, which is a genetic characteristic of myoepithelioma.
EWSR1 rearrangement is present in a subset of myoepithelial tumors of salivary glands with variable morphology and does not correlate with clinical behavior.
The molecular confirmation of diagnosis using RT-PCR is necessary to do the differential diagnosis with other entities, in particular with myoepithelioma that shows similar morphological features and EWSR1 and FUS genes rearrangement.
EWS RNA-binding protein 1 gene (EWSR1) rearrangement is found in 45% of cutaneous, soft tissue and bone myoepithelial neoplasms, and pleomorphic adenoma gene 1 (PLAG1) aberrations are found in 37% of EWSR1-negative soft tissue myoepitheliomas.
To evaluate if this is a recurrent event, an additional cohort of 22 EWSR1-rearranged ME cases lacking a fusion partner were screened by FISH for abnormalities in PBX3 gene.
Herein we describe a soft tissue myoepithelioma arising in the pelvis with an EWSR1-ATF1 fusion, therefore extending the spectrum of partner genes of EWSR1.
The SEER database was queried to find cases of mesenchymal tumors associated with EWSR1 translocations: Ewing sarcoma; clear cell sarcoma; extraskeletal myxoid chondrosarcoma; myxoid liposarcoma; desmoplastic small round cell tumor; and myoepithelial tumor.
Recently, EWSR1 rearrangement has been described in a subset of soft tissue myoepithelial tumors, whereas the cutaneous counterparts showed this aberration in a minority of cases.
EWSR1-POU5F1 fusion in soft tissue myoepithelial tumors. A molecular analysis of sixty-six cases, including soft tissue, bone, and visceral lesions, showing common involvement of the EWSR1 gene.
EWS RNA-binding protein 1 gene (EWSR1) rearrangement is found in 45% of cutaneous, soft tissue and bone myoepithelial neoplasms, and pleomorphic adenoma gene 1 (PLAG1) aberrations are found in 37% of EWSR1-negative soft tissue myoepitheliomas.
We determined that 14 tumors, including eight of 10 lipoblastomas, two of seven gastrointestinal stromal tumors, one of two angiomyofibroblastomas, one of five synovial sarcomas, one of seven leiomyomas and one of 12 myxofibrosarcomas were positive for PLAG1, whereas all seven soft tissue myoepitheliomas were PLAG1 negative.
To evaluate a possible genetic relationship between these soft tissue and salivary gland tumors, PLAG1 expression levels and the genomic status of PLAG1 and HMGA2 were investigated in five soft tissue myoepitheliomas and one pleomorphic adenoma.