Pathological evaluation of the visceral pleura in the radical pleurectomy/decortication for malignant pleural mesothelioma patients

摘要

Background: Radical pleurectomy/decortication (P/D) is applied as a surgical treatment of resectable malignant pleural mesothelioma (MPM). Although P/D removed visceral pleura, dissection plain was not histologically explored previously. We examined a pathological evaluation of surgically removed visceral pleura in P/D. Methods: Twenty-five patients with MPM who underwent P/D at the Tokyo Medical and Dental University Hospital between April 2010 and April 2018 were studied. The 25 cases included 20 with epithelioid tumors, 4 with a biphasic tumor and 1 with desmoplastic tumors. Nine, 1, 11 and 4 patients had mesotheliomas of stages I, II, III and IV, respectively. We analyzed the site of the visceral pleural lesions using the HE & Elastica van Gieson (EVG) staining. The tumor involvement of the pleura and the surgical dissection plane were defined using the depth criteria, D0–3. We added survival analyses according to the depth criteria. Results: Ninety-nine lesions in total 45 lobes: 20 upper right, 14 middle, 20 lower, 22 upper left, and 23 lower were examined. Based on the depth D 0–3 criteria, there were 21 type D0, 18 type D1, 22 type D2 and 38 type D3 lesions. The growth of tumor cells in the pleura was partially diffuse or nodular in all cases. While 38 lesions which invaded the lung parenchyma were excised, another 61 lesions that reached within the pleura were dissected from lung parenchyma. Type D2&3 showed poor survivals than type D0&1. Conclusions: The lung parenchyma was always the dissection plane in P/D, regardless of tumor involvement in the visceral pleura. The depth criteria would help us in classifying pleural invasion histologically and possibly predicting the prognosis.