Petroclival myoepithelial tumour

Case contributed by Dr Maxime St-Amant


Right-sided ophthalmoplegia.

Patient Data

Age: 20
Gender: Male

There is a lobulated right-sided petroclival mass. It is homogeneously T1 hypointense/T2 hyperintense   and shows speckled internal and thin peripheral enhancement. It has mild positive mass effect on the right medial temporal lobe and markedly compresses the ipsilateral Meckel cave. There is some mass effect on the posterior aspect of the right cavernous sinus and no definite cleavage plane. There is no bone erosion.

Expected changes post right pterional craniotomy for biopsy of the right petroclival lesion.

The previously described lesion appears cystic with scattered areas of peripheral calcifications. There is no bone matrix.

Case Discussion

Right-sided petroclival mass for which the favoured diagnosis was extra-osseous chordoma as there is no bone destruction. Chondrosarcoma is another possibility but there is no chondroid matrix on CT and no bone destruction, making this less likely.



  • the tumour consist of cords and occasional nests of spindled and epithelioid cells with well-defined cell membranes surrounded by abundant myxoid and chondromyxoid stroma
  • physaliphorous-like cells with vacuolated cytoplasm are identified with scattered foamy macrophages 
  • mitosis: <1/10 HPF with no dedifferentiated areas and no necrosis
  • immunohistochemistry:
    • S100 and GFAP +
    • variable positivity for MNF116, AE1/AE3 and CAM5.2
    • negative for EMA, SMA and p63

FINAL DIAGNOSIS:  Petroclival myoepithelial tumour

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Case information

rID: 58301
Case created: 11th Feb 2018
Last edited: 19th Feb 2018
Inclusion in quiz mode: Included

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