脳腫瘍内嚢胞液の生化学的分析—その診断的価値

BIOCHEMICAL ANALYSIS OF CYST FLUID OF BRAIN TUMOR

I．はじめに

　脳腫瘍に嚢胞形成をみる事は稀でない。又嚢胞形成を伴う腫瘍は多種にわたるが，概して神経膠腫に頻発する。例えば荒木^1）は大脳半球グリオームの約1／3〜1／4は嚢胞性腫瘍であるとしている。その他嚢胞形成は頭蓋咽頭腫，血管芽腫，下垂休腺腫，聴神経腫瘍，髄膜腫，転移性腫瘍等でも認める事が出来る。

　さて，これら嚢胞性腫瘍の場合，腫瘍が壁在結節を形成したり，嚢胞内壁が腫瘍組織で囲まれている場合は，腫瘍組織診断が容易である。

Astrocytoma, ependymoma, hemangioblastoma, craniopharyngioma and pituitary adenoma make a cyst in the brain frequently. In these cystic braintumors, it is diagnosed histologically if a mural nodule is found or if the inner wall is partially covered by tumor. However, when the inner wall of the cyst is smooth and the mural nodule is not found, histological diagnosis is hardly obtained.

So we analyzed the encysted fluid of brain tumors obtained at the operation for the examination of the nature of tumor.

Cyst fluid of 25 cases in total has been examined: the tumors taken from these patients at operation were diagnosed histologically on 24 occasions.

Cystic fluid and blood serum were examined for total protein, amino acid nitrogen, electrolyte, enzyme, lipid and others in these 25 cases re-spectively.

In general there is a reasonable degree of agree-ment between the biochemical and histological di-agnoses.

Lipid: Phosphatic acid, cholesterol and total lipid in glioblastoma multiforme showed higher level than those in astrocytoma and hemangioblastoma. In the level of cholesterol, astrocytoma was below 130 mg/dl, hemangioblastoma between 50 and 60 mg/dl and glioblastoma multiforme above 150 mg/dl.

Enzyme : Glutamic oxalacetic transaminase (G.O.T.), glutamic phosphatic transaminase (G.P.T.), lactate dehydrogenase (L. D. H.) and alkaline phos-phatase were examined. In the level of L. D. H., astrocytoma was between 150 U. and 400 U., glio-blastoma multiforme above 700 U. and craniopharyn-gioma between 700 U. and 4, 000 U..

In L. D. H. isozyme, astrocytoma and hemangio-blastoma showed high level in Li, L2, L3 isozymes and craniopharyngioma in L4, L5 isozymes as well.

Even if we cannot obtain the histological diagnosis, we can diagnose the nature of tumor, i. e., benign or malignant, by examining L. D. H., L. D. H. isozyme, total lipid, and cholesterol of the encysted fluid of tumor.

With regard to cause of encystment fluid, our findings support that cyst fluid was a filtrate of serum and therefore it was due to local-increased permeability of the blood-brain barrier rather than to increased metabolic demands for a specific material or lysis of neoplastic cells.