Metastasis of malignant pleural mesothelioma to maxillary gingiva: A case report and literature review

Oral cavity metastasis of malignancies is infrequent and that of malignant pleural mesothelioma (MPM) is extremely rare. A 66-year-old man was referred to our hospital complaining of a growing tumor at the left buccal gingiva of the maxilla (L12). The tumor was 15 mm diameter, accompanying a diffuse absorption of the maxillary alveolar bone. The tumor consisted of atypical epithelioid cells forming trabecular or alveolar structure. These cells had various sized nuclei containing clear nucleoli and were positive for calretinin and CAM5.2. He had no history of asbestos exposure but had suffered MPM at left lung apex and right lower lobe for 4 months. Taken together, the tumor was diagnosed as metastasized epithelioid-type MPM. Then, MPM metastasized to left second rib, third thoracic vertebra, lung hilar lymph nodes and an intra-pelvic muscle. Despite chemotherapy and radiation therapy, his conditions deteriorated and he died after a month. Only 21 cases of malignant mesothelioma with metastasis to oral cavity have been reported. Among the cases, tongue and gingiva are high prevalence sites and epithelioid-type is the major cell type. The present patient is the fourth case of MPM metastasis to the maxillar gingiva and the time between diagnosis of primary MM and oral metastasis was the shortest among the epithelioid-type cases. Together with the 21 cases the present case alerts oral and maxillofacial surgeons to be aware of malignant mesothelioma metastasis to oral cavity.