FALSE-NEGATIVE POSITRON-EMISSION-TOMOGRAP HY (PET) IN THE DIAGNOSIS OF A PRIMARY BRAIN LYMPHOMA

We report the case of an AIDS patient with a biopsy-proven primary CNS lymphoma who presented a solitary lesion of the brain which was hypom etabolic on PET but with a high number of EBV genome copies in his cer ebrospinal fluid (CSF). Considering the contradiction between EBV, PCR , and PET, a brain biopsy was carried out. Histological analysis of th e lesion revealed an extensively necrotic intermediate grade immunocyt oma of the brain. The importance of the necrosis offered a possible ex planation for the hypometabolic activity of the lesion on PET. We disa gree with a recent publication and conclude that the hypometabolic act ivity of a brain lesion does not rule out the diagnosis of lymphoma.