Primary central nervous system lymphoma with no enhancement initially and no significant progression over a long term: a case report and review of the literature.

Primary central nervous system lymphoma, a rare primary intracranial tumor, is highly malignant and usually associated with poor prognosis. Recent years, owing to the remarkable progress in intervention techniques, survival time reported has been significantly prolonged. Strategies targeting alleviation and remission are primarily depended on the early diagnosis. However, due to the heterogeneity of the clinical symptoms and imaging features, the disease is frequently misdiagnosed especially in the early phase, rendering a delay of optimal treatment. Herein, we reported the case of a 61-year-old man who was initially misdiagnosed as demyelinating encephalopathy. MRI images showed multifocal lesions across the cerebral cortex and deep white matter, which are not strengthened on contrast enhancements. In respect of clinical symptoms, no significant progress was observed over about 11 months. Finally, the diagnosis was revealed by brain biopsy. After reviewing all the images of the patient, we found that the corpus callosum was involved early in the course of the disease. Therefore, for multifocal intracranial lesions involving the corpus callosum, we should always be vigilant about the possibility of primary central nervous system lymphoma. Histopathological examination of brain biopsy is helpful for early definitive diagnosis.