病理学的にみたアスベスト関連疾患の診断

Diagnosis of Asbestos Exposure-related Diseases Based on Pathological Features

井内 康輝

肺癌

日本で補償・救済の対象となるアスベスト曝露の関連疾患は,非腫瘍性疾患としては石綿肺,良性石綿胸水,びまん性胸膜肥厚が,腫瘍性疾患では肺がん,中皮腫があげられるが,いずれも病理学的立場からの診断における問題点が指摘できる.石綿肺については,末梢肺での細気管支周囲の線維化は小葉中心から末梢へ拡がることが特徴とされるが,近年では蜂窩肺型ないしはUIP型のアスベスト肺が数多く観察され,診断基準として,沈着するアスベスト小体あるいは繊維の存在に頼らざるを得ない.胸水細胞診でがん性胸膜炎と診断できる率は高いが,中皮腫の診断率は約30%と低い.これら胸腔の悪性腫瘍の存在を否定してはじめて,良性石綿胸水は診断できる.アスベスト曝露による肺がんは腫瘍の病理学的所見から診断できるものではなく,肺がんの発生リスクを2倍に高める量の曝露があったことを,画像所見あるいはアスベスト小体ないし繊維の定量で証明できることを根拠としている.様々な調査から日本における中皮腫の病理診断は,現状では約10%程度は誤診であると考えられる.適切な免疫組織化学的染色を行うことなどによって,中皮腫の病理診断の精度をあげていく努力が必要である.

Asbestos exposure-related diseases, which receive compensation or relief funds in Japan, are asbestosis, benign asbestos pleurisy and diffuse pleural thickening as non-neoplastic disease, lung cancer and mesothelioma as neoplastic disease, and some pathological problems awaiting solutions have been pointed out, in each of those diseases. Asbestosis is known to show characteristic peribronchiolar fibrosis extending to the periphery of lobules, however, recently the type with honey-comb appearance and the type with resemblances to usual interstitial pneumonia (UIP) are observed very often, and therefore, the diagnostic criteria have changed depending on asbestos bodies or fibers deposited in the peripheral lung. By cytology of pleural effusion, the diagnostic rate of cancerous pleuritis is high, however, that of mesothelioma is only approximately 30%. Benign asbestos pleurisy can be diagnosed when no malignant tumor is identified in the pleural cavity. Etiological diagnosis as exposure to asbestos-related lung cancer cant be made by means of the pathological findings of tumor, and it is based on imaging by CT or MRI and the measurement of asbestos bodies or fibers, and required findings can certify the exposure level to asbestos doubles the occurrence of lung cancer. On the basis of various studies, pathological diagnosis in Japan at present includes misdiagnosis at the level of about 10%. Efforts are necessary to improve the accuracy of pathological diagnosis as mesothelioma by means of adequate immunohistochemical staings or others.

石綿肺

胸水

細胞診

肺がん

中皮腫

Asbestosis

Pleural effusion

Cytology

Lung cancer

Mesothelioma

医学 [ 490 ]

日本語

日本肺癌学会

Copyright (c) 2009 日本肺癌学会

[ISSN] 0386-9628

[NCID] AN00203978

[DOI] 10.2482/haigan.49.83

[URI] http://joi.jlc.jst.go.jp/JST.JSTAGE/haigan/49.83 ～の異版である