Ectomesenchymal chondromyxoid tumor: A neoplasm characterized by recurrent RREB1-MKL2 fusions Journal Article
| Authors: | Dickson, B. C.; Antonescu, C. R.; Argyris, P. P.; Bilodeau, E. A.; Bullock, M. J.; Freedman, P. D.; Gnepp, D. R.; Jordan, R. C.; Koutlas, I. G.; Lee, C. H.; Leong, I.; Merzianu, M.; Purgina, B. M.; Thompson, L. D. R.; Wehrli, B.; Wright, J. M.; Swanson, D.; Zhang, L.; Bishop, J. A. |
| Article Title: | Ectomesenchymal chondromyxoid tumor: A neoplasm characterized by recurrent RREB1-MKL2 fusions |
| Abstract: | Ectomesenchymal chondromyxoid tumor is a rare and benign neoplasm with a predilection for the anterior dorsal tongue. Despite morphologic heterogeneity, most cases are characterized by a proliferation of bland spindle cells with a distinctive reticular growth pattern and myxoid stroma. The immunophenotype of these neoplasms is likewise variable; most cases express glial fibrillary acid protein and S100 protein, with inconsistent reports of keratin and myoid marker expression. The molecular pathogenesis is poorly understood; however, a subset of cases has been reported to harbor EWSR1 gene rearrangement. Following identification of an RREB1-MKL2 fusion gene by RNA Sequencing in an index patient, a retrospective review of additional cases of ectomesenchymal chondromyxoid tumors was performed to better characterize the clinical, immunohistochemical, and molecular attributes of this neoplasm. A total of 21 cases were included in this series. A marked predisposition for the dorsal tongue was confirmed. Most cases conformed to prior morphologic descriptions; however, hypercellularity, hyalinized stroma, and necrosis were rare attributes not previously emphasized. The neoplastic cells frequently coexpressed glial fibrillary acid protein, S100 protein, keratin, smooth muscle actin, and/or desmin; a single case was found to contain significant myogenin expression. An RREB1-MKL2 fusion product was identified in 19 tumors (90%), a single tumor (5%) had an EWSR1-CREM fusion product, and the remaining case lacked any known fusion gene by RNA Sequencing. The latter 2 cases subtly differed morphologically from many in the cohort. This series illustrates that recurrent RREB1-MKL2 fusions occur in most, perhaps all, cases of ectomesenchymal chondromyxoid tumor. © 2018 Wolters Kluwer Health, Inc. All rights reserved. |
| Keywords: | gene rearrangement; tongue; ewsr1; crem; ectomesenchymal chondromyxoid tumor; mkl2; rreb1 |
| Journal Title: | American Journal of Surgical Pathology |
| Volume: | 42 |
| Issue: | 10 |
| ISSN: | 0147-5185 |
| Publisher: | Lippincott Williams & Wilkins |
| Date Published: | 2018-10-01 |
| Start Page: | 1297 |
| End Page: | 1305 |
| Language: | English |
| DOI: | 10.1097/pas.0000000000001096 |
| PROVIDER: | scopus |
| PMCID: | PMC6133728 |
| PUBMED: | 29912715 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 1 November 2018 -- Source: Scopus |
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