PMC5875109_01
Preoperative MRI revealed the lesion identified in the left superior frontal gyrus (a-d). The lesion showed hyperintensity on T2WI (a) and FLAIR (b). The lesion demonstrated slight hypointensity on T1WI (c) and does not exhibit mass effect, contrast enhancement (d), or associated edema. Postoperative MRI (16 months after operation) showed total resection and the removed cavity with no evidence of tumor recurrence by T2WI (e), FLAIR (f), and T1WI (g)
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F1
However, MRI revealed a 25 mm x 17 mm, nonenhanced lesion with gadolinium in the left superior frontal gyrus as a hypointense mass in T1-weighted imaging (T1WI) and hyperintense in T2-weighted imaging (T2WI) and fluid attenuated inversion recovery (FLAIR) without any mass effect or edema [Figure 1a-d]. He remained stable without recurrence of the lesion on MRI at the 16-month postoperative follow-up [Figure 1e-g].
The lesion was resected in an en bloc fashion (a). Microscopy with low power magnification demonstrating a well-demarcated subcortical lesion abutting gray and white matter (b, hematoxylin and eosin stain (H and E)). Alpha-internexin (INA) expression is detected in tumor stroma (c) and Kluber-Barrera (KB) staining confirms the absence of myelin in the tumor lesion (d). The lesion demonstrates clear delineation from the surrounding brain without evidence of infiltration (e-f, H and E)
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F2
We could resect the tumor en bloc and performed total resection of tumor [Figure 2a]. The lesion had a multinodular appearance laying on the gray-white matter junction under low-power magnification microscopic examination [Figure 2b-d]. We could see alpha-internexin expression in tumor stroma [Figure 2c] and the proliferation of cells resembling ganglion cells, with eccentric round nuclei, foamy, and relatively ample eosinophilic cytoplasm [Figure 2e and f].
The neuronal tumor cells are intensely stained by HuC/HuD (a), but negatively or weakly stained for neuronal nuclear antigen (NeuN) (b), synaptophysin (c) and nuclear oligodendrocyte transcription factor (Olig2) (d). The ganglioid cells are unreactive for glial fibrillary acidic protein (GFAP) (e)
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F3
On immunohistochemical analysis with neuronal antigens, the tumor cells showed positive staining for HuC/HuD [Figure 3a]. The neuronal tumor cells demonstrated weak to moderate cytoplasmic immunoreactivity to neuronal nuclear antigen (NeuN), synaptophysin, and nuclear oligodendrocyte transcription factor (Olig2) [Figure 3b-d]. The ganglioid cells showed negative staining for glial fibrillary acidic protein [Figure 3e].