Mesenchymal chondrosarcomas showing immunohistochemical evidence of rhabdomyoblastic differentiation: a potential diagnostic pitfall

Andrew L. Folpe, Rondell Graham, Anthony Martinez, David Schembri-Wismayer, Jennifer Boland, Karen J. Fritchie

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The diagnosis of mesenchymal chondrosarcoma, a distinctive biphasic malignant neoplasm harboring the HEY1-NCOA2 gene fusion and consisting of primitive round to spindled cells admixed with foci of relatively mature hyaline cartilage, is usually straightforward by morphologic evaluation alone. However, in the setting of a limited biopsy, specimens lacking cartilage generate a broad differential diagnosis, encompassing a variety of other primitive sarcomas, including spindle cell/sclerosing rhabdomyosarcoma. Although a small number of cases of mesenchymal chondrosarcoma with aberrant skeletal muscle marker expression have been reported, pathologists are largely unaware of this potential diagnostic pitfall. We report 6 additional cases of mesenchymal chondrosarcoma showing expression of multiple skeletal muscle markers, including one case initially misdiagnosed as “spindle cell/sclerosing rhabdomyosarcoma” on needle biopsy. Awareness of this phenomenon and judicious application of molecular diagnostic testing for the HEY1-NCOA2 fusion are critical to avoid misclassification of mesenchymal chondrosarcoma as rhabdomyosarcoma, with potentially adverse patient impact.

Original languageEnglish (US)
Pages (from-to)28-34
Number of pages7
JournalHuman Pathology
Volume77
DOIs
StatePublished - Jul 1 2018

Keywords

  • Desmin
  • Mesenchymal chondrosarcoma
  • MyoD1
  • Myogenin
  • Rhabdomyosarcoma

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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