悪性胸膜中皮腫が疑われた心外膜原発性悪性中皮腫—1剖検例の報告と心外膜悪性中皮腫の本邦報告例における他臓器侵襲についての考察

Primary malignant mesothelioma of the pericardium masquerading as malignant pleural mesothelioma:Report of an autopsy case and review of the reported cases in Japan as to its invasion to neighboring organs

　悪性胸膜中皮腫が連続的に心外膜を侵襲することはよく知られている。このため，臨床的に胸腔内の悪性腫瘍が疑われ，胸水と心嚢液貯留がある場合，それは肺癌や悪性胸膜中皮腫が心外膜へ2次的に浸潤したものと考えるのが一般的である。我々は，まれな心外膜原発性悪性中皮腫が逆に胸膜へ浸潤し，胸水と心嚢液貯留を来たし，胸水細胞診にて悪性胸膜中皮腫が疑われた症例を経験した。その自験剖検例を報告し，収集しえた51例の心外膜悪性中皮腫の本邦報告例につき，主に他臓器への転移・浸潤について考察を加える。

The Patient was a 72 year-old man who presented with dyspnea and general fatigue. Chest X-ray and CT-scan at the admission showed bilateral pleural effusion with collapse of the left lung and pericardial effusion. Cytology from the left pleural effusion sug-gested malignant mesothelioma. For this reason, malignant mesothelioma of the left pleura was diagnosed clinically and it was supposed to have spread subsequently to the pericardium.

At autopsy, entire surface of the heart was found to be encroached in a diffuse fashion by a thick layer of mesothelioma tissues, which formed a small mass around the left pulmonary vein over the left atrium and invaded deep into the myocardium of all cardiac chambers. The endocardium and the intima of the left pulmonary vein were free of the invasion. The parietal pericardium adhered in places to the cardiac lesion, but no direct invasion to the adjacent pleurae through the pericardial wall was present. The left pleura over the lung and chest cavity disclosed only a superficial invasion by similar mesothelioma which was identifiable only on microscopic study. No distant metastasis was present in any thoracic and other organs as well as lymph nodes including the hilar ones of the lung.

It seemed most likely from this anatomical finding that the primary site of the present mesothelioma was in the pericardium (visceral) and the tumorspread to the left pleura by a continuous extension along the outside of the left pulmonary vein.

Primary malignant mesothelioma of the pericar-dium is of very rare occurrence and we found only 51 cases of it in the Japanese literature since 1915. Metastasis and/or direct invasion to other organs bythis neoplasm was found positive in 67% of the 52 cases including ours, and its continuous spread to neighboring organs appeared characteristic (31% in the myocardium, 25% in the lung, and 19% in the pleura).