Case Number : Case 2196 - 8 November 2018 Posted By: Raul Perret

Definitely beautiful physaliphorous cells.

Odd location but agree whit anh. 

Chordoma is my first choice. 

Chordoma periphericum or parachordoma? Would be interesting to know Raul's opinion on this controversy. He must have done IHC for brachyury. 

My Colleagues are really skill in soft tissue tumors. I long thought of a Myoepithelioma/mixed tumor, but have to suck it up and agree with them! 

12 hours ago, anh said:

Definitely beautiful physaliphorous cells.

Yes! definitely phisaliphorous cells. As Anil said, Chordoma periphericum should be a better definition. 

Vincenzo,

you might actually be right about myoepithelioma. Assuming this is not a metastatic chordoma (brachyury would help as Anil had mentioned), this tumor is probably a parachordoma / myoepithelioma. Some authors believe it's the same tumor (myoepithelioma) . I guess Raul will have some kind of molecular finding and explains the concept of parachordoma / myoepithelioma.

Very interesting. Either metastatic chordoma or primary soft tissue chordoma. Clinical history is required in this case, I guess.

Yes, this is a case of extra-axial chordoma. In the original diagnosis I suggested to rule out the possibility of a metastasis from a primary axial chordoma. A CT-scan was performed which showed no tumor in the axial skeleton, proving that this was a true extra axial chordoma.

The term parachordoma has been used in the past for myoepithelial tumors showing massive vacuolation (hence simulating a chordoma). Some of these cases probably represented extra axial chordomas that were missed due to the absence of more specific markers like brachyury. Personally, I avoid using this terminology.

Interestingly, the diagnosis of the referring pathologist was a myoepithelioma, this is a comprehensible mistake due to the morphological and immunophenotypical overlap seen between this tumor and chordoma. The main clue is the physaliphorous cells and the expression of brachyury.

These tumors have overall a good prognosis with only rare cases developing metastasis (mainly lung). I suggest you to read this article for more information on this pathology.

Hope you guys liked the case and thanks for the comments.

Here a little table I did with the "pearls" of this entity