PMC2801848_01
PMC2801848_02
Axial MRI obtained before biopsy shows diffuse hyperintensity on T2-weighted images in the pons (a) and extending to the temporal lobes bilaterally (b). Preoperative FLAIR image also demonstrates the lesion in the pons and temporal lobes (c). One month postoperative and post-chemotherapy axial T2-weighted images demonstrate substantial resolution of the lesion in the pons (d) and cerebral hemispheres (e)
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Fig1
T2 (Fig. 1a) and FLAIR (Fig. 1b) imaging in the pons, with extension to the medulla and midbrain, cerebellum, right frontal cortex, and bilateral temporal lobes, with extension to the Sylvian region and right parietal lobe. There was no mass effect or midline shift.   The postoperative MRI at 1 month showed almost complete resolution of brainstem and cerebral lesions (Fig. 1c, d).
Pathologic specimens obtained from stereotactic biopsy demonstrated diffuse lymphocytic infiltrate in the specimen from the pons (a). Spongiform changes in the white matter and malignant infiltration in Virchow-Robbins spaces were also noted. Magnification of 100x demonstrates malignant lymphocytes (b). The cortical specimen demonstrated subpial infiltration (c). The malignant lymphocytes present in the specimen from the pons stained positive for CD3 (d) and TdT (e). The specimen demonstrated a high Ki-67 labeling index(f)
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Fig2
Brainstem biopsy specimen showed atypical lymphocytic infiltrate with prominent reactive astrocytosis and spongiform changes in the white matter (Fig. 2a, b). Subpial spread of malignant cells was noted in the cortical specimen (Fig. 2c). Immunohistochemical analysis demonstrated positive staining for the T-cell marker CD3 (Fig. 2d), CD7, CD45, CD10, CD99 (data not shown), and were weakly positive for both CD1a and CD5 (data not shown). TdT (Fig. 2e). The specimen also exhibited a high Ki-67 labeling index (Fig. 2f).