急性出血性白質脳炎と鑑別を要した中枢神経系原発悪性リンパ腫の1例

A case of primary central nervous system lymphoma mimicking acute hemorrhagic leukoencephalitis

中枢神経系原発悪性リンパ腫（primary central nervous system lymphoma：PCNSL）は免疫正常例では均一な造影効果を呈することが多いが，まれに出血や非典型的な造影パターンを示し，脱髄性疾患との鑑別が困難となる。今回我々は，脳内多発出血とopen-ring状増強を呈し，びまん性大細胞型B細胞リンパ腫（diffuse large B-cell lymphoma：DLBCL）と診断された症例を経験したので報告する。

We present a case of a man in his 70s who presented with multiple intracerebral hemorrhages and open-ring enhancement. Although initial biopsy findings suggested acute hemorrhagic leukoencephalitis, the patient was ultimately diagnosed with primary central nervous system lymphoma（PCNSL）. PCNSL typically demonstrates homogeneous contrast enhancement but rarely presents with hemorrhage or open-ring enhancement, which can mimic demyelinating diseases. This case taught us that PCNSL should not be ruled out even when such findings are present.