Primary leptomeningeal lymphoma presenting as cerebellopontine angle lesion.

We report a primary leptomeningeal lymphoma (PLML) presenting as a cerebellopontine angle lesion. CT showed slight enlargement of the ventricular system, obliteration of the basal cisterns and a dense lesion in the left cerebellopontine angle which enhanced with contrast medium. Cerebrospinal fluid abnormalities included sterile lymphocytic pleocytosis without malignant cells, low sugar and high adenosine deaminase levels. An erroneous diagnosis of tuberculous meningitis was made, but autopsy revealed a leptomeningeal B-cell lymphoma with infiltration of the middle cerebellar peduncle giving the appearance of a cerebellopontine angle lesion. Seven cases of cerebellopontine angle lymphoma have previously been described, only one of which could be classified as PLML.