and Gene Fusion-Associated Mesenchymal Tumors: Clinicopathologic Correlation and Literature Review.

The spectrum of mesenchymal tumors associated with rearrangements of the gene has been growing in recent years due to progress in molecular detection techniques. Originally identified as the gene involved in the pathogenesis of Ewing sarcoma, the gene is now known to be rearranged in diverse clinical and histopathological entities. The gene is one of the many translocation partners of in gene fusions in a morphologically typical, albeit rare, subgroup of mesenchymal tumors. Little is known about the clinical characteristics of tumors containing gene rearrangements since most of the few reports published describe molecular rather than clinical aspects. In the current study, we report three patients with tumors carrying the gene translocation, including one rare primary tumor of soft tissues. Another patient with a benign-appearing bone tumor with a unique gene translocation is described. In various mesenchymal tumors (e.g., myxoid/round cell liposarcoma, low-grade fibromyxoid sarcoma, or angiomatoid fibrous histiocytoma), the gene, as a member of the TET family, may be alternatively rearranged instead of the gene without any noticeable influence on the microscopical appearance or clinical outcome. This fact seems not to apply to mesenchymal tumors with the involvement of the gene because both in our experience and according to the extensive literature review, they have different properties on the morphological and molecular level. Both and fusion-carrying tumors do not show microscopical or clinical features of Ewing sarcoma.