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多嚢胞性腹膜中皮腫は中皮由来の稀な良性腫瘍で、進行すると完全摘出が困難で再発の可能性が高い。当院で経験した多嚢胞性腹膜中皮腫の2症例を報告する。症例1は35歳、2経産。経腟分娩後の1ヵ月健診時に17cmの多房性腫瘤を指摘されMRIより多嚢胞性腹膜中皮腫を疑い腹腔鏡手術を施行した。病理診断は多嚢胞性腹膜中皮腫であった。術後約3ヵ月で再発し増大傾向であったため、術後9ヵ月で2度目の腹腔鏡手術を施行し腫瘍を摘出した。症例2は45歳、3経産。5cmの左卵巣腫瘍の診断で腹腔鏡手術を施行したが、腸間膜に播種した状態であり腫瘍減量のみで終了。組織診断後6ヵ月で2度目の腹腔鏡手術を施行し可能な限り残存腫瘍を摘出した。3年後、診断目的に3度目の腹腔鏡手術を施行し、術前経腟超音波検査では指摘できなかった小嚢胞病変を認め再発と考えられた。多嚢胞性腹膜中皮腫は再発しやすく低侵襲な腹腔鏡手術は治療・管理に適していると考えられる。(著者抄録)

Generally, malignant sarcomatoid mesothelioma (MSM) has few desquamated tumor cells in the ascitic effusion when compared to those of epithelioid type, and is said to present difficulty in cytopathological diagnosis. There are few reports of the cytopathological features of MSM. We report herein cytopathological features of tumor cells found in ascites of a 58-year-old male patient with MSM. In ascitic fluid, sarcomatoid large atypical polygonal and short spindle cells with irregular nuclei, irregular membranous invagination, and distinct nucleoli were seen. Although there is no definite evidence of mesothelial differentiation in sarcomatoid atypical cells in the ascitic fluid by immunostaining, a diagnosis of peritoneal malignant mesothelioma was made according to the histopathological features of a surgical peritoneal sample and the clinical course of this patient. When various sarcomatoid atypical cells are seen in the ascitic fluid, it seems to be necessary to include MSM in the differential diagnosis.

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.

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.

2012