Intraoperative cytologic diagnosis of chordoid meningioma. A case report

Chordoid meningioma is an uncommon supratentorial tumor in which a cordonal pattern on a mucofibrillar background covers areas of classic meningioma with a diffuse, meningeal, immunohistochemically reactive pattern. Its cytology has not been described before.

A 45-year-old woman with headaches and a poorly defined, nondiplopic vision alteration underwent magnetic resonance imaging, which showed a tumor in the upper part of the left orbital cavity. An intraoperative squash smear showed closely knit, pseudosyncytial plates composed of medium-sized cells with homogeneous nuclei and nuclear pseudoinclusions. There were some physaliferouslike, loose cells without cytoplasmic vacuolation and a fairly abundant, metachromatic, pink to light purple background that was absent inside the plates. A diagnosis of meningioma with a possible chordoid pattern was made. No frozen intraoperative section was prepared. Histology showed 90% chordoid meningioma merging with areas of classic meningothelial meningioma and overall positivity for epithelial membrane antigen and vimentin. S-100 was negative.

A reliable intraoperative cytologic diagnosis of chordoid meningioma can be made because the morphology is highly characteristic. Close cellular association and the cells' nuclear traits are expected in a meningioma. The metachromatic background can cause a false diagnosis of chordoma. However, there are some clear differences in the cells and their relation to the mucofibrillar matrix that make the diagnosis definitive.