Left periventricular mass demonstrating a homogeneous, T2 iso- to hyperintense mass with patchy enhancement post gadolinium and prominent restricted diffusion.

An initial CT (not shown) demonstrated a homogeneously hyperdense mass.

The lack of prominent enhancement is atypical. 

MR spectroscopy revealed: Large Choline peak with reversed choline:creatinine ratio. Prominent lactate peak is also seen. Prominent inositol peak is also seen.

Findings are nonetheless consistent with primary CNS lymphoma.