OVERVIEW
Extraskeletal myxoid chondrosarcomas (EMC) are a rare form of soft tissue sarcoma that usually develops in the deep tissues of the arms or legs, most often in middle-aged to older adults. Although it can appear in other parts of the body, such as the trunk or head and neck, these cases are much rarer. It is characterized by rearrangements involving the NR4A3 (CHN) gene, with the majority of cases harbouring a t(9;22)(q22;q12.2) that results in the fusion of the 5’ portion of EWSR1 (22q12.2) with the 3’ portion of NR4A3 (9q31.1). Other fusion partners include TAF15 (17q12) or FUS (16p11.2) that fuse the 5’ portion of the gene to the 3’portion of NR4A3. Rearrangement involving NR4A3 and other fusion partners are also identified in acinic cell carcinoma of salivary gland origin and in a subset of uterine epithelioid leiomyosarcomas.
TEST REQUIREMENTS
- Completed CGL Cytogenetics Solid Tumour Testing requisition form
- FFPE Tumour specimen (see Specimen Guidelines, Cytogenetics FISH FFPE test type)
- An H&E stained slide with the tumour region circled, and the estimated % tumour content written in the Tumour Content field of the requisition. NOTE: A minimum of 10% tumour and at least 200 nuclei is required.
- Specimen block and/or at least one unstained slide for each probe requested.
- See our FFPE Guidelines for additional details.
TURN-AROUND TIME
Results are reported within fourteen days from receipt of specimen and completed requisition form.
RESULTS REPORTING
- Specimens are reported as Positive for a rearrangement, Negative for a rearrangement.
METHOD
FISH analysis is performed on the provided paraffin embedded tissue using the NR4A3 (9q22.3-q31.1) dual colour, break-apart probe (Cytocell).
REFERENCES
- Agaram NP, Zhang L, Sung YS, Singer S, Antonescu CR. Extraskeletal myxoid chondrosarcoma with non-EWSR1-NR4A3 variant fusions correlate with rhabdoid phenotype and high-grade morphology. Hum Pathol. 2014;45(5):1084-1091. doi:10.1016/j.humpath.2014.01.007
- Brown JM, Rakoczy K, Pretell-Mazzini J. Extraskeletal myxoid chondrosarcoma: Clinical features and overall survival. Cancer Treat Res Commun. 2022;31:100530. doi:10.1016/j.ctarc.2022.100530