[Lymphomatosis cerebri as the cause of leukoencephalopathy]

Lymphomatosis cerebri (LC) is an infrequent type of primary lymphoma of the central nervous system that is characterised by diffuse, infiltrating involvement of the white matter of the brain without the formation of a mass.

To report the case of a patient with LC in order to draw attention to this disease, which is rarely diagnosed, and to its initial presentation in magnetic resonance imaging (MRI) as leukoencephalopathy.

Our patient was a 56-year-old female who had clinical signs and symptoms of sub-acute dementia. Computerised axial tomography and MRI of the head revealed extensive, diffuse and bilateral involvement of the white matter, basal nuclei, mesencephalon and pons, with no mass effect or contrast enhancement. A stereotactic biopsy of the white matter (which was not conclusive) showed a perivascular mixed mononuclear-cell inflammatory infiltrate of B and T cells. No cytologic atypia was observed. Treatment was established with corticoids, which produced a clinical and radiological improvement in the first two months. During the next month the patient underwent rapid clinical deterioration with sleepiness and a worsening of the ability to walk. In an MRI scan the lesion had a more heterogeneous appearance with mass effect on adjacent structures and patchy contrast enhancement. A wedge biopsy of brain tissue led to a diagnosis of high-grade B-cell lymphoma.

The imaging and histological appearance of LC may not be the one typically found in primary lymphomas of the central nervous system, and its clinical presentation may be similar to that of other diffuse processes involving compromise of the white matter (cerebral gliomatosis, inflammatory diseases of the white matter, such as Behçet's disease, Sjögren's disease or systemic lupus erythematosus).