Heterogeneous genetic profiles in soft tissue myoepitheliomas

Myoepithelioma, mixed tumor and parachordoma are rare soft tissue tumors thought to represent different morphologic variants of the same family of tumors, hereafter referred to as MMP tumors. The genetic basis of these neoplasms is poorly investigated. However, they morphologically resemble mixed tumor of the salivary glands (a.k.a. pleomorphic adenoma). This is the first study characterizing whole genome DNA copy number changes in MMP tumors and the genomic imbalances detected in four MMP tumors and one pleomorphic adenoma were diverse. The only recurrent aberration of known importance for tumor development was homo- and heterozygous deletions of the region in 9p21-22 which harbors the CDKN2A and CDKN2B genes. Defined by the deletion in case 3, the region 1.27-4.82 Mb on chromosome 19 was heterozygously lost in all cases, including the pleomorphic adenoma. A complex pattern of aberrations was seen in the primary tumor of case 2 with amplifications, interrupted by normal copy numbers and losses, of regions on chromosomes 6, 9, and 13. Keywords: comparative genomic hybridization, soft tissue myoepithelioma, mixed tumor, parachordoma, pleomorphic adenoma Cases 1-3 and 5-6 were analyzed using 32k array CGH and male genomic DNA (Promega) was used as reference.