Ectomesenchymal chondromyxoid tumor of the oral cavity: a report of 5 new cases with comprehensive review of the literature and clinicohistopathologic features

Abstract

Objective: An ectomesenchymal chondromyxoid tumor (ECT) is an uncommon soft tissue tumor with an enigmatic histogenesis and striking predilection for the tongue. We present 5 new cases and review the literature.

Study design: We performed a retrospective search for ECTs within the University of Kentucky Oral Pathology Biopsy Service and the published literature.

Results: Five new cases from the biopsy archives and 103 well-documented ECT cases from the literature were compiled and reviewed. Whereas 89.8% of ECT are found on the anterior/dorsal/lateral/unspecified tongue, 4.6% are on the posterior/base of tongue. Six extralingual cases are reported. The age ranges from 2.3 to 78 years with an average of 40. Most ECT react with GFAP (92.8%) and S-100 protein (91.3%). Whereas 21/23 cases demonstrated a RREB1-MKL2 fusion, EWSR1 gene mutations are identified in 4 cases.

Conclusions: Most ECT are readily diagnosed on routine histopathology in combination with tumor site, immunohistochemical findings, and molecular findings; however, a subset share overlapping features with myoepithelioma of soft parts. As further molecular analysis is performed on this tumor, we may find that a subset of previously diagnosed ECT relate to or represent myoepithelioma or conversely fall under the spectrum of the pluripotent ECT.