Presentation
Left-sided head tilt associated with left-sided gait abnormality for 5 days. Concern for posterior fossa mass.
Patient Data
There is an expansile, infiltrative, nonenhancing mass centered within the right pons that displays low T1 signal, intermediate T2 signal, and reduced diffusivity. There is associated mass effect on the left anterolateral aspect of the fourth ventricle.
Case Discussion
This is a case of a diffuse midline glioma (formerly known as a diffuse intrinsic pontine glioma).
The patient underwent resection of the brainstem tumor. Hematoxylin and eosin stained slides show a high grade neoplasm with markedly increased cellularity. The tumor cells were ovoid or round in shape and have scant cytoplasm. In immunohistochemical stains, the tumor cells were positive for vimentin and SALL4, and weakly positive for GFAP in scattered tumor cells. A subset of tumor cells (50%) were positive for p53. Rare cells show weak membranous staining for D2-40. Immunostain for INI-1 shows positive/retained nuclear staining in tumor cells. Neurofilament-positive neurites are extensively seen within the tumor, reflecting the likely infiltrating nature of the tumor. Ki-67 proliferation index is markedly elevated, with focally up to 80%.
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