Primary diffuse leptomeningeal oligodendrogliomatosis with an isolated 1p deletion.

We report a case of primary diffuse leptomeningeal oligodendrogliomatosis with an isolated 1p deletion confirmed by fluorescent in situ hybridization (FISH) analysis in 52 year-old man. The MRI scan in a patient presenting with progressive headache, nausea and diplopia revealed diffuse leptomeningeal thickening and enhancement without definitive evidence of an intraparenchymal lesion. Biopsy of thickened, enhancing meninges within the left sylvian fissure revealed subarachnoid proliferation of oligodendroglial cells with varying degrees of de-differentiation and sparing of the underlying cortex. An isolated 1p deletion was confirmed by FISH analysis. This is the first reported adult case of a 1p deletion in primary diffuse leptomeningeal oligodendrogliomatosis.