PMC4123265_01
(a) T1-weighted coronal view. Hypointense nodular image in the floor of the left lateral ventricle, producing mild-moderate, noncommunicating hydrocephalus. (b) T1-weighted sagittal view. Note the involvement of the brainstem, which explains the symptoms of the patient. (c) T1-weighted axial view showing a nodular, hypointense lesion with small cystic areas in its interior. (d) Axial view, FLAIR. Note the absence of perilesional edema, and the lack of contrast enhancement
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F1
Nevertheless, the patient also underwent a computerized tomography (CT) scan, and magnetic resonance imaging (MRI), which showed an isodense lesion [Figure 1].
(a) Gross anatomy of resected tumor, showing a fibroelastic, whitish mass. (b) H and E stain of the mass, exhibiting the characteristic rounded cells with small nuclei and scarce cytoplasm over an abundant fibrillary matrix and cystic spaces. Note the absence of atypical mitoses. (c) Immunohistochemistry stain for neurospecific enolase, showing negativity in the majority of the cells. (d) Immunohistochemistry stain for glial fibrillary acidic protein (GFAP), exhibiting strong positivity
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F2
Immunohistochemistry was positive for glial fibrillary acidic protein (GFAP) and negative for neurospecific enolase, which was compatible with grade I subependymoma, according to the World Health Organization (WHO) classification [Figure 2].