Miliary brain metastasesの1剖検例

An Autopsy Case of Miliary Brain Metastases

精神症状にて発症し，頭部MRIでmiliary brain metastasesと診断した症例を報告した。症例は死亡時58歳男性。57歳時，異常行動で発症し，頭部CT，髄液検査とも異常なく，巣症状にも乏しく診断が困難であった。しかし，頭部MRIにて多発結節性病変を認め，喀痰細胞診の結果などより，肺腺癌による転移性脳腫瘍と診断した。MRIにて脊髄への転移は認められなかった。全経過約8カ月。病理学的特徴として，転移巣はびまん性にみられたが，大脳皮質に比べ白質には極端に少なく，延髄には病巣を認めなかった。組織学的には腫瘍結節周辺部に浮腫，反応性グリオーシスは認めず，管腔形成した腫瘍細胞が集簇し，腫瘍が血管周囲腔を通じて脳軟膜に浸潤していた。Miliary metastasesの剖検例は少なく，また本例は頭部CTと頭部MRI所見の不一致が認められ，特にFLAIR画像，造影MRIが病巣検出に優れていた。病理学的にも転移病態機序を考える上で貴重な症例である。

A 57-year-old man was admitted to our hospital with a diagnosis of psychiatric emergency.His symptoms were similar to encephalitis, metabolic encephalopathy or acute depressive psychosis because of poor focal neurological signs.Laboratory examinations, including routine hematological and biochemical investigations, serum vitamin B₁, B₁₂ levels, and cerebrospinal fluid obtained by lumbar puncture, were normal.Brain CT was also normal, therefore it was difficult to make a diagnosis.But, we could clinically diagnose him as having pulmonary adenocarcinoma with numerous metastatic nodules of the brain.Because miliary lesions in the cerebral hemispheres, brainstem and cerebellum were disclosed on brain MRI.Furthermore, chest CT revealed the lung tumor in the left S₈ area.In addition, laboratory examination showed a rise of tumor marker and cytologic examination of sputum revealed class V.Fluid-attenuated inversion recovery and contrast-enhanced MR images demonstrated more prominently miliary metastases, in particular lesions in the cerebral cortex, than T1- and T2-weighted images.There was neither edema in the surrounding region of metastatic nodules nor mass effect on all MR images.Spinal MRI showed no metastatic lesions.The patient died of respiratory failure at the age of 58, about eight months after the disease onset.The brain weighed 1,575 g.Neuropathological findings revealed diffuse miliary brain metastases located in all parts of the brain, except for the medulla oblongata.Histological examination disclosed multiple metastases from a well-differentiated adenocarcinoma with a predominant tubular pattern.There was neither edema nor glial reaction in the surrounding area of metastatic lesions.Many pseudorosettes were recognized and carcinoma cells, extending through perivascular spaces into the subarachnoid space, were noticed.