PMC3909849_01
Imaging features of cerebellar subependymoma in 28-year-old man.. A. Unenhanced axial CT scan demonstrates well-defined cystic and solid mass with multiple calcifications (black arrow) in left cerebellum. B-E. Mass exhibits iso- to hypointensity (relative to normal gray matter) on axial T1-weighted MRI and hyperintensity on axial T2-FLAIR. There were multiple, small, high-signal intensity lesions (black arrow) suggesting calcifications on T1-weighted imaging, and numerous dot-like low-signal intensities suggesting microcysts (thin white arrow) on T2-FLAIR. On DWI, mass exhibited hypointense signal (relative to gray matter) on DWI without diffusion restriction and increased ADC relative to brain parenchyma. There is no evidence of peritumoral edema, mass effect or intratumoral hemorrhage. Mass was near fourth ventricle, but clearly separated from it. Isointense area (thick white arrows) suggesting normal cerebellar white matter was observed between mass and fourth ventricle. F, G. On axial and coronal contrast-enhanced MR images, there was no enhancement in solid portion or peripheral wall, and normal parenchyma was clearly identified between mass and fourth ventricle (white arrow). H. Cerebral angiograms did not reveal feeding vessel or tumor staining. I. Microscopic images showing clustered cellular neoplastic proliferation with islands of high nuclear density with dense, abundant fibrillary matrices. Round and isomorphic nuclei were observed, but mitosis was not seen (HE; original magnification, x 40). FLAIR = fluid attenuated inversion recovery, DWI = diffusion-weighted image, ADC = apparent diffusion coefficient, HE = hematoxylin and eosin
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F1
Pre-contrast CT revealed a well-defined cystic and solid intraaxial mass with internal calcifications in the cerebellum, which measured 4.3 x 3.5 cm (Fig. 1A). T1-weighted image and hyper intensity on the T2-weighted image (Fig. 1B, C). There was no evidence of peritumoral edema around the mass and no enhancement of the mural nodule or cyst wall on the gadolinium-enhanced T1-weighted image. Diffusion-weighted image showed iso- or low-signal intensity without diffusion restriction while the same lesion was increased ADC relative to brain parenchyma (Fig. 1D, E). The mass was located near and displaced the fourth ventricle; however, it did not communicate with the ventricle, and normal parenchyma was clearly identified between the mass and the fourth ventricle on the thin-section three-dimensional T1-weighted images (Fig. 1F, G). Cerebral angiograms demonstrated a rather hypovascular mass; neither feeding vessels nor tumor staining was visualized (Fig. 1H). The tumor cell nuclei were round and isomorphic, but active mitosis was not observed (Fig. 1I).