Well-differentiated Papillary Mesothelioma of the Pleura Diagnosed by Video-Assisted Thoracic Surgical Pleural Biopsy: A Case Report

Well-differentiated papillary mesothelioma of the pleura (WDPM-P) is an extremely rare type of mesothelial tumor that is thought to be of low malignant potential. Herein, we report on a case of WDPM-P. A 74-year-old woman was admitted for evaluation of shortness of breath. Pleural effusion was observed in the right thorax. Computed tomography after chest drainage did not reveal any lung or pleural tumors. Abnormally high levels of hyaluronic acid were detected in the pleural effusion. Cytological examination of the effusion revealed Class V findings; however, it was difficult to distinguish mesothelioma from adenocarcinoma. Because immunological evaluation may have provided more information, video-assisted thoracic surgical pleural biopsy (VATS-PB) was performed. Biopsied frozen specimens were revealed to be mesothelioma, and so localized pleurectomy and partial resection of the diaphragm were performed. Pathological examination established a diagnosis of WDPM-P. Six years postoperatively, the patient is doing well. As demonstrated in the present case, combined VATS-PB and pathological studies are useful for the diagnosis of and determination of surgical indications for pleural malignancies