January 7, 2022
Dural-Based Extra-Axial Mass
Figure 1: Hematoxylin and eosin 100x original magnification
Greater than 90% of the lesion was comprised of elements seen in the lower left half of this image. The upper right half of this image shows morphologic features of meningothelial meningioma, including the presence of several psammoma bodies. The lower left half of the images shows transition to neoplastic cells arranged in small nests and chords within a background of variably vacuolated myxoid material (i.e. chordoma-like).
This 50-year-old patient presented with visual changes and word-finding difficulties. Brain MRI demonstrated a 4.6 x 4.5 x 3.5 cm well-circumscribed contrast-enhancing dural-based extra-axial mass, with dural tail and mass effect on the left frontal lobe. The lesion was gross totally resected.
What is your diagnosis based on Figures #1 through #4?
A. Chordoid meningioma
B. Pilocytic astrocytoma
Figure 2: Hematoxylin and eosin 100x original magnification
The upper right corner again shows more typical appearing meningioma transitioning into neoplastic cells arranged in chords within a myxoid background. Mitotic figures were rare (less than 1 per 10 high power fields), and no necrosis or brain invasion was seen.
Figure 3: Hematoxylin and eosin 200x original magnification
Higher magnification showing neoplastic cells arranged in chords within a vacuolated myxoid background.
Figure 4: Alcian blue PAS 200x original magnification
This histochemical stain highlights the background myxoid material (blue tinctoral quality).
Answer: Chordoid meningioma
The morphologic features are consistent with the pathologic diagnosis of chordoid meningioma. This meningioma subtype has a propensity for local recurrence and is therefore considered a WHO grade 2 lesion.
The overall morphologic features of this dural-based extra-axial mass are not those of glioblastoma, pilocytic astrocytoma, or lymphoma. Other considerations, in this case, include tumor-to-meningioma metastasis (a rare phenomenon), chordoma (cytokeratin, S100 protein, and brachury positive), and chordoid glioma of the third ventricle (GFAP and TTF1 positive).
Sangoi AR, Dulai MS, Beck AH, Brat DJ, Vogel H. Distinguishing chordoid meningiomas from their histologic mimics: an immunohistochemical evaluation. Am J Surg Pathol. 2009 May;33(5):669-81. doi: 10.1097/PAS.0b013e318194c566. PMID: 19194275; PMCID: PMC4847145.
Couce ME, Aker FV, Scheithauer BW. Chordoid meningioma: a clinicopathologic study of 42 cases. Am J Surg Pathol. 2000 Jul;24(7):899-905. doi: 10.1097/00000478-200007000-00001. Erratum in: Am J Surg Pathol 2000 Sep;24(9):1316-7. PMID: 10895812.