緩徐進行性に発症し，癌性髄膜炎との鑑別を要したアテローム血栓塞栓性梗塞の1例

A Case of Atherothrombotic Embolization Developing with Slowly Progressive Symptoms and Requiring Differential Diagnosis from Metastatic Tumor Recurrence

Ⅰ．はじめに

　特に癌の既往を有する症例において，多発性で散在性の亜急性期脳梗塞は癌性髄膜炎としばしば鑑別が困難なことがある．その理由の1つとして，造影magnetic resonance imaging（MRI）ではともに高信号を示し，急性期の脳梗塞で有用な拡散強調画像（diffusion-weighted image：DWI）でも亜急性期に入るとびまん性に広がる高信号域として描出され，癌性髄膜炎と類似した所見が認められるからである．また，画像上判断できないような虚血状態を代謝率から調べるmagnetic resonance spectroscopy（MRS）も病変が微小な場合は適用が困難である⁴⁾．今回，肺癌の脳転移に対する術後の長期経過観察中に緩徐進行性の麻痺が出現し，脳梗塞と癌性髄膜炎の鑑別が問題となった1例を経験したので報告する．

　We report a case of atherothrombotic embolization that developed with slowly progressive symptoms and required differential diagnosis from metastatic tumor recurrence. A 64-year-old man with a history of lung cancer and metastatic brain tumor was carefully followed at our outpatient department for tumor recurrence. Five years after surgery for brain metastasis and whole brain radiation therapy, he had no recurrence and systemic disease was well controlled. At a routine follow up in October 2013, he complained of slight right arm dysesthesia. Follow up brain magnetic resonance（MR）imaging revealed no lesion. Two months later, he developed right hemiparesthesia and gait disturbance. Spinal MR imaging was unremarkable. However, at a routine follow up in January 2014, multiple enhancements were detected near the resection cavity and regions delineating the sulci. At first, this was diagnosed as tumor recurrence. However, 3 days later, additional MR imaging detected new multiple small infarctions after worsening right hemiparesis and dysarthria. With the diagnosis of embolic stroke, we searched for an embolic source. Cardiogenic embolization and carotid bifurcation stenosis studies were negative, but severe stenosis and thrombosis were detected near the left common carotid artery origin. This site was in the field of radiation the patient received as treatment for primary lung cancer.