Home > G. Tumoral pathology > myxoid chondrosarcoma

myxoid chondrosarcoma

Tuesday 24 August 2004

Digital case

- JRC:78 : Soft tissue (buttock): Low grade myxoid chondrosarcoma (vs soft tisue myoepithelioma)

Microscopy

Conventional myxoid chondrosarcoma is composed of lobules of uniform spindle cells with limited eosinophilic cytoplasm forming a delicate reticular pattern in a myxoid background.

The rare high-grade variant of extraskeletal myxoid chondrosarcoma is characterized by cords of large epithelioid cells in a myxoid matrix. Like conventional extraskeletal myxoid chondrosarcoma, the high grade form may show rhabdoid cytomorphology, mimicking the plasmacytoid cells with nuclear atypia seen in some myoepithelial carcinomas.

Focal S100 or EMA is found in a minority of extraskeletal myxoid chondrosarcomas but GFAP and keratin are negative.

Cytogenetics

Extraskeletal myxoid chondrosarcomas (EMCs) are characterized by recurrent chromosome translocations resulting in fusions of the nuclear receptor TEC to various NH(2)-terminal partners.

- t(9;22)(q22;q12) (NR4A3/EWSR1)
- t(9;17)(q22;q11)
- t(9;15)(q22;q21)

Secondary translocations

- t(1;16)(q21;q13) (#9408761#)

Molecular biology

- NR4A3/EWSR1 fusion gene by t(9;22)(q22;q12) (or CSMF/EWSR1)
- NR4A3/TAF2N
- NR4A3/TAF15 ( or NR4A3/RBP56)
- NR4A3/TCF12

Differential diagnosis

- myoepithelia carcinoma of soft tissue
- soft tisue myoepithelioma

References

- SMARCB1/INI1 protein expression in round cell soft tissue sarcomas associated with chromosomal translocations involving EWS: a special reference to SMARCB1/INI1 negative variant extraskeletal myxoid chondrosarcoma. Kohashi K, Oda Y, Yamamoto H, Tamiya S, Oshiro Y, Izumi T, Taguchi T, Tsuneyoshi M. Am J Surg Pathol. 2008 Aug;32(8):1168-74. PMID: #18580682#