[A case of malignant peritoneal mesothelioma without deletion of p16]

The patient was a man in his 60s with a history of 2 operations for the treatment of malignant neurogenic tumors. Partial resection of the stomach and liver was performed in December 2006, followed by chemotherapy with adriamycin and interferon; resection of a recurrent tumor in the left subphrenic space was performed in December 2007. In June 2011, recurrent tumors were detected in the lesser curvature of the stomach body and left inferior quadrant of the abdomen (12 mm [SUVmax 7.9] and 23 mm [SUVmax 10.5], respectively)by using 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET). The tumors resected in August 2011 were diagnosed as malignant peritoneal mesothelioma on immunohistochemical analysis. In February 2013, FDG-PETrevealed a 20-mm tumor of in the mesentery with a SUVmax of 7.6, and the tumor was resected. This secondary tumor had the same features of the previously resected malignant mesothelioma. Fluorescence in situ hybridization revealed no deletion of the p16 gene, and the patient had had no other recurrence during follow-up. Malignant peritoneal mesothelioma is a rare disease, accounting for 10% of all malignant mesothelioma cases, with low rates of p16 gene deletion compared with malignant pleural mesothelioma. Previous studies have reported that the lack of p16 deletion is associated with better prognosis in malignant pleural mesothelioma. Herein, we report of a patient diagnosed with malignant peritoneal mesothelioma, without deletion of the p16 gene, who survived for over 2 years and 10 months after initial diagnosis of malignant mesothelioma.