大きな髄外病変を伴った胸髄髄内腫瘍の1例

Intramedullary Tumor of the Thoracic Spinal Cord with Large Extramedullary Lesions. Case Report

　髄外病変を伴った胸髄髄内腫瘍（capillary hemangioma）の稀な1例を経験した．主訴は腰・両下肢のしびれと痙性麻痺による歩行障害であった．MRIではTh8レベルにT1強調像で等信号，ガドリニウムで均一に増強される雪だるま状病変を認めた．またT2強調像では脊髄の腫大と広範な髄内高信号病変を認めた．ミエロおよびミエロCTでは同部位での完全ブロックと脊髄腫大像，右側偏位を認めた．手術所見では，硬膜切開すると白濁したくも膜内にかなり大きな多房性髄外腫瘍を認めたが，髄内との交通は明らかでなかった．髄外腫瘍全摘後，脊髄は急速に膨張し軟膜直下に暗赤色の腫瘍が認められた．後正中部で脊髄を縦割して，栄養動脈を凝固切離しながら剝離し，一塊として摘出した．術後病理診断では毛細血管性血管腫であった．髄内病変の診断は難しく，一見，髄外腫瘍の画像所見を示すので注意は必要である．MRIによる血管系髄内腫瘍の鑑別診断は可能と思われた．

　We recently encountered a rare case of an intramedullary tumor of the thoracic spinal cord with large extramedullary lesions. The patient had experienced numbness of his waist and both lower extremities and spastic paresis with gait disturbance. Magnetic resonance imaging showed a uniformly enhanced intramedullary and extramedullary mass at Th8 with spinal cord swelling manifested as a high intensity area on the T2-weighted image. Myelography revealed complete block due to spinal cord swelling with a shift to the right side at Th8. At surgery multiple tassel-shaped extramedullary tumors covered with thick arachnoid membrane were observed. Dorsal rootlets entered the extramedullary tumor, but it was unclear whether the extramedullary tumor was connected to the intramedullary tumor. As soon as the extramedullary tumor was resected, however, the spinal cord expanded, and a dark-red tumor appeared under the pia mater. The feeding arteries were coagulated through the posterior central sulcus and the tumor was dissected from the spinal cord and excised en bloc. It was difficult to diagnose the intramedullary lesion preoperatively masked by the extramedullary lesion. The differential diagnosis of the intramedullary vascular tumors seemed to be possible by magnetic resonance imaing.