Well-differentiated Papillary Mesothelioma of the Pleura : A Series of 24 Cases

Well-differentiated papillary mesothelioma is an unusual variant of epithelial mesothelioma considered to be of low malignant potential. The majority of previously reported cases developed in the peritoneum of young women without a history of asbestos exposure. The authors report 14 cases of well-differentiated papillary mesothelioma, seven of which originated in the pleura, six in the peritoneum, and one in the tunica vaginalis. Eleven of the patients were male and three were female, with an average age at presentation of 58 years (range 32-82 years). Six of the patients had a quantifiable history of asbestos exposure. Of the nine cases with complete follow-up, six had clinically indolent disease, one showed resolution after adjuvant chemotherapy, one pursued an aggressive course, and one died of other causes. These findings indicate that well-differentiated papillary mesothelioma is a rare variant of mesothelioma with a variable clinical prognosis that is etiologically related to asbestos exposure in some cases.

Twenty-two cases of well-differentiated papillary mesothelioma of the peritoneum (WDPMP) are described. Eighteen of the 22 patients were women. The peritoneal tumor was usually multifocal. Many of the tumors appear to be indolent or inactive and for practical purposes are benign. However, a few patients receiving adjuvant therapy have died under circumstances that make it difficult to determine whether the tumor was responsible for the death. It is suggested that adjuvant therapy be withheld from patients with WDPMP, unless there is clear evidence of progression. The cause of these rare tumors is not apparent, although three patients had had possible exposure to asbestos and two were sisters.