Friday, August 13, 2010

Support grows for use of brachyury immunohistochemistry in chordoma

Nirmala A. Jambhekar, MD and colleagues from Mumbai, India recently revisited the immunohistochemical marker brachyury in chordoma in the pages of the Archives of Pathology & Laboratory Medicine (August 2010;134:1181-1187). In a validation study of 51 cases, the authors refer to brachyury as a "new age" marker, perhaps because it was discovered by means of gene expression profiling. (I should mention that the name "brachyury" comes from the Greek brakhus meaning short and oura meaning tail, as it was a gene first described by researchers as one that affected the tail length of lab animals.) The authors found that brachyury staining was positive in 46 of the 51 chordomas and negative in all 58 of the non-chordomatous tumors examined for comparison.

The study endorses the utility of brachyury as part of an immunohistochemical panel when a chordoma diagnosis is being considered. The photo below, taken from the article, depicts the nuclear staining for brachyury one sees in chordoma:
Of course, in classic chordomas derived from classic anatomic locations, immunohistochemistry is hardly necessary. However, as the authors state, "the variable nature of the chondromyxoid matrix, presence of bland spindly cells, and at times paucity of physaliphorous cells poses diagnostic difficulties. For therapeutic purpose, distinct recognition of myxoid chondrosarcomas, dedifferentiated chondrosarcomas, and mucinous adenocarcinomas is valuable."

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