脊椎骨肉腫の“en bloc”切除標本から得た新知見―病理から手術へのフィードバック

Novel Viewpoints Obtained from En Bloc Specimens of Spinal Osteosarcoma. : Feedback to Surgery from Pathology

　3例の脊椎骨肉腫（脊髄を含めて切除した再手術例，脊髄を含めて切除した初回手術例，術前化学療法が奏効した初回手術例）を一塊として全摘出する機会を得た．その大割切除標本を病理学的に詳細に検討した結果，臨床的に有益ないくつかの知見を得ることができた．まず，硬膜は腫瘍浸潤に対する強いバリアとなっていたが，硬膜という強いバリアでも，腫瘍の脊柱管内への浸潤が長期にわたると，バリアは徐々に破壊されてくることが明らかとなった．さらに，骨肉腫では腫瘍と硬膜の間に偽被膜は存在せず，腫瘍は硬膜と癒着していた．よって実際の手術の際には，腫瘍を硬膜から慎重に剝離しなければ硬膜表面に腫瘍が残存することが懸念される．ただし，術前化学療法が奏効していた症例では，腫瘍の表面に反応性偽被膜が形成されており，手術での剝離は容易であった．また，初回手術後の瘢痕組織はバリアとはなっておらず，瘢痕内に腫瘍が浸潤していた．よって再手術の際には，できる限り瘢痕も含めた切除が必要であるといえる．脊髄に関しては，1カ月も完全麻痺が続いた場合には，病理学的に脊髄はすでに壊死に陥っており，回復の見込みは全くないことが証明された．

　We performed en bloc excision of 3 cases of spinal osteosarcoma. As a result of detailed pathological examination of the resected specimens, the some useful viewpoints were obtained clinically. First, although the dura mater was a strong barrier to tumor invasion, this barrier was gradually destroyed, when invasion into the spinal canal lasted over a long period of time. Furthermore, no “pseudomembrane” existed between the tumor and dura, and the tumor had adhered to the dura completely. Therefore, in an operation, it is difficult to dissect the tumor from the dura, and we are anxious about tumor remnant around the dura. However, a “pseudomembrane” was formed in the circumference of tumor in the case in which chemotherapy had taken effect before the surgery. Dissection between the tumor and dura was easier in this case. Second, scar tissue after a virgin surgery did not become a barrier, and the tumor had invaded the scar tissue. Therefore, it is necessary to excise tumors including any scar tissue as much as possible in the case of re-operation. Third, nerve cells in the spinal cord had already lapsed into degenerative necrosis pathologically when complete paraplegia lasted for a month or more. It was clear that there was no hope of recovery of spinal cord function.