PMC3551505_01
(a-c) Axial (d, e) coronal, and (f) sagittal T1 post-gadolinium MRI demonstrating a heterogeneously-enhancing, partially cystic mass in the left frontal lobe / anterior fossa. The mass extends anteriorly and inferiorly to the cribriform plate at the skull base just above the ethmoid sinus, seen clearly in a, d, and f
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F1
A MRI of the brain with and without contrast confirmed a large left frontal mass (7.4 cm x 4.3 cm x 5.1 cm) that was heterogeneously enhancing, partially cystic, and caused adjacent vasogenic edema [Figure 1].
The tumor is composed of bland mesenchymal spindle cells with ovale pointed nuclei (panel a, H and E, x200), which stains only with antibodies to vimentin (panel b, x200). At the ultrastructural level (panel c), the cells have elongated, irregular nuclei and relatively abundant cytoplasm continuing in slender processes. Overall, their appearance is consistent with a mesenchymal neoplasm, but they lack features to suggest a precise lineage of differentiation. The FGF-23 gene analysis by rtPCR[1] demonstrated positive amplification within tumor cells (panel d)
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F2
Collectively, these results were consistent with a diagnosis of histologically benign PMTMCT [Figure 2].