Fulminant bilateral cerebellar syndrome in a patient with chronic lymphocytic leukemia

A 55 year old patient with chronic lymphocytic leukemia (CLL) and long-standing excessive lymphocytosis developed a rapidly progressive neurological syndrome. Differential diagnosis focused on two rare neurological complications in this disease: direct brain infiltration by leukemic cells versus progressive multifocal leukoencephalopathy (PML). Tissue diagnosis was not available. Two cerebro-spinal fluid examinations performed during the presence of the acute neurological symptoms were normal. Computed tomography (CT) showed low density lesions without enhancement and no mass effect within the left cerebellum. Magnetic resonance imaging scan (MRI) demonstrated multiple hyperintense areas in the brain stem, right and left cerebellum and right capsula interna, suggestive of demyelinative process. In our opinion these findings were compatible with the diagnosis of PML, but biopsy was not performed. Because of the different therapeutic approach in these two conditions, we feel that tissue diagnosis is warranted in patients with CLL who develop a rapidly progressive central nervous system complication in the presence of normal CSF.