[A case of CNS metastasis from gastric MALT lymphoma]

Recently, the incidence of primary CNS lymphoma (PCNSL) is increasing. Metastatic CNS lymphoma occurs much less than PCNSL. We report the case of a 53-year-old man who presented with CNS metastasis from gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The symptoms at the time of diagnosis were dizziness and aphasia. MRI revealed a left parietal lobe tumor with a large peritumoral edema. About 4 years ago, he had suffered from gastric MALT lymphoma with a high grade component. Eradication of Helicobacter pylori led to remission of the disease 18 months after the treatment. From his past history, the brain tumor was suspected of being a metastatic lymphoma. Stereotactic biopsy revealed diffuse large B-cell lymhoma. Histopathological findings including lymphocytic subsets were almost identical between the primary gastric MALT lymphoma and metastatic brain lymphoma. Complete remission was obtained by repeated high-dose methotrexate chemotherapy. There has been no recurrence for 5 years without additional therapy. This case is probably the first report of CNS metastasis from gastric MALT lymphoma.