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SMARCA2‐NR4A3 is a novel fusion gene of extraskeletal myxoid chondrosarcoma identified by RNA next‐generation sequencing
Author(s) -
Wei Shuanzeng,
Pei Jianming,
von Mehren Margaret,
Abraham John A.,
Patchefsky Arthur S.,
Cooper Harry S.
Publication year - 2021
Publication title -
genes, chromosomes and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.754
H-Index - 119
eISSN - 1098-2264
pISSN - 1045-2257
DOI - 10.1002/gcc.22976
Subject(s) - chromosomal translocation , biology , exon , microbiology and biotechnology , desmin , fusion gene , pathology , synaptophysin , immunohistochemistry , cancer research , gene , vimentin , genetics , medicine , immunology
Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain differentiation, characterized by recurrent chromosomal translocation involving NR4A3 (9q22.33) in more than 90% of cases. Five fusion partners for NR4A3 have been described including: EWSR1 (22q12.2), TAF15 (17q12), FUS (16p11.2), TCF12 (15q21), and TFG (3q12.2). This report describes a patient with an EMC at the dorsum of the right foot. The tumor showed a cord‐like and reticular pattern in a background of myxoid matrix. The tumor cells demonstrated an epithelioid morphology with prominent nucleoli. The tumor cells were positive for synaptophysin, GFAP, with focal positivity for CD117, S100, Cam5.2, and NSE, and negative for AE1/3, desmin, and SMA. An RNA next‐generation sequencing test showed a SMARCA2‐NR4A3 gene fusion which has not been previously reported. The exon 3 of SMARCA2 was fused to exon 3 of NR4A3 . This fusion was confirmed by NR4A3 break‐apart FISH, although both SMARCA2 (9p24.3) and NR4A3 (9q22.33) are located on chromosome 9. The tumor cells showed retained expression of INI1 and SMARCA2 by immunohistochemistry.