August 2007: A 40-year-old woman with a progressive periventricular white matter lesion - Diagnosis: Diffusely infiltrating germinoma

A 40-year-old woman presented with blurred vision and diplopia, followed by slowly progressive left-sided motor and sensory disturbances. She also suffered from memory loss and had mild spatial and temporal disorientation. A T2-weighted MRI showed a large area of high signal intensity in the periventricular white matter of the right more than the left occipital region and the corpus callosum, without enhancement on T1-weighted images after gadolinium administration and without mass effect. A stereotacticbiopsy of the intracerebral lesion showed blast-like neoplastic cells within a mononuclear infiltrate. No diagnosis could be made based on morphology and immunohistochemistry using a large series of markers. However, based on positive OCT3/4 nuclear staining, the tumor was diagnosed as a germinoma (seminoma of the brain). The patient was treated accordingly and her condition improved, although focal deficits remained.