[Demyelinating pseudotumoral lesion prior to a primary cerebral lymphoma]

Some case of demyelinating pseudotumoral lesions preceding the appearance of primary cerebral lymphoma have been reported. The relation between the two conditions is not known. We report the case of a woman in whom a demyelinating pseudotumoral lesion had been diagnosed on biopsy and who developed a primary cerebral lymphoma 13 months later.

In October 1997 a 38 year old woman presented with a secondarily generalized focal motor seizure. Neuroimaging showed a left frontal tumour with marked oedema and uptake of contrast medium. Based on the clinicoradiological suspicion of a primary cerebral tumour or metastasis, treatment was started with dexamethasone. Approximately two weeks later a stereotaxic biopsy was done, in which there was demyelination with conservation of the axons and perivascular inflammatory infiltration with polyclonal T and B lymphocytes. The diagnosis was 'a pseudotumoral form of a demyelinating disease'. Thirteen months later the patient had episodes of falling to the floor, followed by subsequent slight confusion and difficulty in speaking. On neuroimaging studies (cerebral CAT and MR) there was a tumour of the left basal ganglia, considerable oedema and homogeneous marking following the injection of contrast. Anatomopathological study of the lesion showed a B cell lymphoma.

In cases of pseudotumoral demyelinating lesions the possibility of a primary cerebral lymphoma of the central nervous system must be remembered.