PMC4709897_01
a SWI on the first admission revealed low-signal intensity spotty lesions in the left cerebellar peduncle (arrow). b T2*WI on the first admission. Findings similar to those in Fig. 1a are present (arrow). c Contrast-enhanced MRI on the first admission showed no apparently enhanced lesions, including in the cerebellar peduncle. d SWI obtained three months after the first admission revealed de novo low-intensity spots in the medulla oblongata. e T2*WI obtained three months after the first admission. Findings are to those in Fig. 1d. f Contrast-enhanced MRI obtained three months after the first admission showed no apparently enhanced lesions. g SWI obtained one year after the first admission revealed spreading hypointensity- lesions adjacent to the fourth ventricle (arrows). h T2*WI obtained one year after the first admission. Findings similar to those in Fig. 1g are present. i Contrast-enhanced MRI obtained one year after the first admission showed a slightly enhanced lesion around the fourth ventricle. j SWI on the second admission revealed expanding lesions of the pons and right cerebellar peduncle (arrows). k T2*WI on the second admission revealed findings similar to those in Fig. 1k. l Contract-enhanced MRI on the second admission showed an expanded enhanced lesion around the fourth ventricle
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Fig1
He had been in good health until three years earlier except for the past medical history of hepatitis B, when he presented with transient dizziness without any abnormal findings on MRI (see Additional file 1: Figure S1). Conventional MRI revealed no specific findings, with the exception of three small low-intensity spots located in the left cerebellum on T2*-weighted image (T2*WI) and susceptibility-weighted image (SWI) that were not enhanced by gadolinium (Fig. 1a, b, c). Three months later, follow-up MRI studies revealed enlarged low-intensity lesions in the cerebellum and newly visible lesions in the brainstem with T2*WI and SWI (Fig. 1d, e, f). Nine months later, low intensity lesions were observed in the right cerebellar hemisphere, vermis, and dorsal surface of the brainstem with T2*WI and SWI (Fig. 1g, h, i). With the use of T2*WI and SWI, low-intensity lesions were observed to be increased and expanded in bilateral cerebella and the dorsal brainstem. (Fig. 1j, k, l).
Histological findings of the tumor a and b; h-e stain of the tumor. The tumor is composed of sheets and lobules of large and pale cells with often indistinct cell membranes and somewhat vacuolated cytoplasm. Locally, lymphocytic infiltration is present. c-f Immunohistochemically, tumor cells are positive for c-Kit (c) and strongly positive for SALL4 (d). Also, tumor cells are weakly positive for PLAP (e). The Ki-67 labeling index is high in the tumor cells (f). (Original magnification; A x 200, B-F x 400)
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Fig2
A stereotactic biopsy was performed, targeting the newly enhanced lesion in the left cerebellum; histopathological examination revealed large and round neoplastic cells with lymphocytic infiltration suggestive of a two-cell pattern (Fig. 2a, b). The tumor cells tested immunopositive for c-Kit (Fig. 2c), SALL4 (Fig. 2d), and PLAP (Fig. 2e), characteristic of germinoma. Ki-67 labeling index was high (Fig. 2f).