Seventy-one myoepithelial tumors with available tissue for molecular analysis were retrieved from the surgical pathology and consultation files of the authors. Slides were re-reviewed in corroboration with the immunohistochemical panel in all cases. Minimum criteria for confirming the morphologic diagnosis included the co-reactivity for EMA +/− cytokeratin and S100+/− GFAP. Five cases were excluded as failing FISH analysis: four due to decalcification and one due to hybridization failure.
The tumors were assessed morphologically for pattern of growth, duct formation, clear cell component, epithelioid versus spindle cell composition, nuclear pleomorphism, mitotic activity, and necrosis. The tumor location was recorded, including the anatomic structures involved, and lesions were subclassified into three subgroups, cutaneous, superficial (subcutaneous), and deep (below the fascial plane).
In order to investigate a potential relationship between soft tissue ME tumors and their salivary gland counterpart, we included five salivary gland ME carcinomas (ex-pleomorphic adenoma) for the genetic analysis. A group of five salivary mucoepidermoid carcinomas and five cutaneous eccrine hidradenomas were also tested, as recent evidence suggested similar genetic abnormalities (see Discussion section). As chordoma periphericum has been considered a potentially related tumor, we have included two such examples occurring in the bone, confirmed based on their immunopositivity for t-Brachyury and a similar microscopic appearance with their axial counterpart (Nielsen et al., 2001 (link); Scolyer et al., 2004 (link); Tirabosco et al., 2008 (link)). In addition, three ossifying fibromyxoid tumors (OFT) were included in the analysis, as this tumor often shares morphologic and immunophenotypic features with ME tumors.
The tumors were assessed morphologically for pattern of growth, duct formation, clear cell component, epithelioid versus spindle cell composition, nuclear pleomorphism, mitotic activity, and necrosis. The tumor location was recorded, including the anatomic structures involved, and lesions were subclassified into three subgroups, cutaneous, superficial (subcutaneous), and deep (below the fascial plane).
In order to investigate a potential relationship between soft tissue ME tumors and their salivary gland counterpart, we included five salivary gland ME carcinomas (ex-pleomorphic adenoma) for the genetic analysis. A group of five salivary mucoepidermoid carcinomas and five cutaneous eccrine hidradenomas were also tested, as recent evidence suggested similar genetic abnormalities (see Discussion section). As chordoma periphericum has been considered a potentially related tumor, we have included two such examples occurring in the bone, confirmed based on their immunopositivity for t-Brachyury and a similar microscopic appearance with their axial counterpart (Nielsen et al., 2001 (link); Scolyer et al., 2004 (link); Tirabosco et al., 2008 (link)). In addition, three ossifying fibromyxoid tumors (OFT) were included in the analysis, as this tumor often shares morphologic and immunophenotypic features with ME tumors.
