脊椎管内に進展した腕神経叢原発と考えられるmalignant schwannomaの1剖検例

AN AUTOPSY CASE OF MALIGNANT SCHWANNOMA IN THE BRACHIAL PLEXUS EXTENDING INTO THE SPINAL CANAL

　抄録　左腕神経叢原発と考えられるmalignant schwannomaが頸部硬膜内髄外脊髄腫瘍を呈した1剖検例を報告する。症例は46歳の女性で，死亡約2年前より，左上肢痛，同部の知覚低下および脱力が出現，1年後急速に四肢脱力，上行性の知覚低下，排尿困難が出現し，脊髄腫瘍の診断にて，椎弓切除，頸髄硬膜内腫瘍の亜全摘出を行い，病理組織学的にはmalignant schwannomaと診断された。その後8カ月の経過で，広汎な肺への転移をきたして死亡した。臨床症状および剖検所見より，腕神経叢が原発部位で，頸部脊髄神経根を経て頸髄硬膜へと浸潤し，硬膜内髄外腫瘍として発育したmalignant schwannomaと考えられた。頭頸部領域のmalignant schwannomaは比較的稀であり，腫瘍細胞が腕神経叢から頸部脊髄神経根に沿って脊髄へむかう進展形式をとり，脊髄腫瘍症状を呈したことが，本症例の特異な点と考えられた。

A 46-year-old woman had pain and numbness in the left upper extremity, on Dec. 1982. These symptoms progressed gradually. She was admit-ted to our department on Jan. 26, 1984 because of neck pains and progressive paraplegia. Neuro-logical examination revealed monoplegia of the left arm with absent DTRs, spastic paraplegia, sensory disturbances below Th 11 level and severe sphincter disturbance. A metrizamide myelogram showed intradural extramedullary mass at C 4-7. Laminectomy was immediately performed from C 3 to C 7. A soft and brown tumor was attached at the ventral aspect of the cord at C 3 to C 7 and it was firmly attached at the root sleeve of the C 5 level The histological diagnosis of the tumor was malignant schwannoma. One month later, she was discharged on foot. However, she was re-admitted to our department because of intractable pains in left neck and arm in Aug. '84. The second operation was done on Sep. 15. A soft and brown mass was found intra- and ex-tradurally and it invaded into paravertebral mus-cules. On Sep. 30 '84 she died from respiratory failure.

Postmortem examination revealed that intra-extradural tumor was found at C 4-Th 3, and the left brachial plexus was swollen. In the brachial plexus, the nerve fiber was replaced with tumor in the perineurium. The tumor invaded to the vertebral body and the paravertebral muscles,There were numerous metastasis of the tumor inthe both lungs. The tumor was formed byvariable and scanty cytoplasm with many mitotic丘gures.

The malignant schwannoma in the brachial ple-xus was less common compared with in the extre.mities and trunk. It was extremely rare that themalignant schwannoma formed an intradural ex･tramedullary spinal cord tumor. In the presentedcase, clinical and pathological findings suggestedthat the tumor arose in the brachial plexus andextended into the spinal canal along the nerveroots.