CLINICOPATHOLOGICAL STUDY OF FOUR CASES OF BENIGN LOCALIZED PLEURAL MESOTHELIOMA

Abstract

Four cases of localized mesothelioma were clinicopathologically analyzed. There were one male and three females, with an average age of 54.8. All patients were asymptomatic and pointed out an abnormal shadow on chest X-ray examination at routine medical checkup. With diagnostic imagings and needle biopsy no definitive diagnosis could be made preoperatively. Under a possible diangosis of benign lung tumor, diaphragmatic tumor or mediastinal tumor, thoracotmy was performed. The tumors in case 1, 2 and 4 were present on the visceral pleura. In case 3, the tumor arose from the parietal pleura. Tumors in case 1 and 4 were pedunculated and those in case 2 and 3 were sessile. The size of tumor was 2.8×1.7cm in case 1, 3.5×3.0cm in case 2, 13.0×7.0cm in case 3, or 4.7×4.5cm in case 4. In all cases, the tumors were localized and were removed completely together with a part of surrounding structure. Pathologically the resected tumors were comprized of non-invasive proliferation of fibroblast-like cells without atypia and mitosis, and were diagnosed as benign localized mesothelioma. These tumors were thought to originate from mesenchyme, because electron microscopic examination revealed features of fibroblasts and mesothelial cells. All the patients are doing well and have no signs of recurrence, with the longest disease-free period for 4 years in one patient.