Well-differentiated papillary mesothelioma: clustering in a Portuguese family with a germline BAP1 mutation

Well-differentiated papillary mesothelioma (WDPM) is a rare variant of epithelioid mesothelioma and is considered to be associated with good prognosis due to its clinically indolent behavior and long survival. Most reported cases involve the peritoneum of women at reproductive age with no history of exposure to asbestos, with pleural involvement being less common. The optimal management, including the role of chemotherapy in the treatment of WDPM, remains unsettled. The authors describe two cases of WDPM in women of the same family (siblings); the elder with WDPM of the pleura and peritoneum with a 12-year survival period and the younger with a WDPM of the peritoneum diagnosed in 2011 and uveal melanoma diagnosed in 2012. Neither patient had any known exposure to asbestos fibers or any other mineral carcinogens. After the concurrent diagnosis of WDPM and uveal melanoma, genetic diagnosis was carried out taking into consideration that these two malignancies were recently associated with hereditary BAP1 gene mutations and it was positive for both the patients. To our knowledge, this is the first description of WDPM in two siblings who also presented with a germline BAP1 mutation. This article provides evidence of the wide clinical spectrum of cancer susceptibility associated with a BAP1 germline mutation.