A primary CNS lymphoma in spontaneous remission for 3.5 years after initial detection of the lesions by MRI.

We describe the clinicopathological features of a patient with an autopsy-proven primary CNS lymphoma, who had a relatively long remission period after onset. A 61-year-old man experienced disorientation and gait disturbance. A ventriculoperitoneal shunt operation was performed, based on the diagnosis of hydrocephalus due to aqueductal stenosis, after which his symptoms subsided. Three months later, T2-weighted magnetic resonance imaging (MRI) revealed high-intensity lesions in the corpus callosum and tectum. However, he remained asymptomatic for the next three and a half years, during which periodic MRI studies constantly detected the lesions. At the age of 65 years, he suffered respiratory and consciousness disturbances, and his general condition gradually deteriorated. MRI studies disclosed that the callosal lesion had spontaneously disappeared, whereas the tectal lesion had developed to become an enhanced linear lesion with a tendency to spread on the dorsal side of the brain stem. Examination of the cerebrospinal fluid disclosed a markedly elevated beta2-microglobulin content, and a tentative diagnosis of malignant lymphoma was made. Steroid pulse therapy had little effect, and the patient died four years after presentation. Examination at autopsy disclosed a malignant, large B-cell lymphoma that had diffusely infiltrated the cerebrum and brain stem. In the corpus callosum, a small number of residual lymphoma cells were seen around the vessels. Therefore, the initially detected lesions in the corpus callosum and tectum might have been attributable to lymphoma, and the unusual clinical and radiological features of this case provide further information that might aid in diagnosis and help to ensure prompt treatment.