We present 2 cases of malignant peritoneal mesothelioma (MPM) characterized by a localized solid mass without ascites and showing F-FDG uptake. A 79-year-old man with a history of asbestos exposure suffered from an epithelioid MPM originating from the hepatoduodenal ligament with FDG uptake (SUVmax 16.8). Another 80-year-old man with esophageal cancer showed desmoplastic MPM of the small bowel mesentery with FDG uptake (SUVmax 4.0). Desmoplastic MPM is more aggressive and yields poorer prognosis compared with the epithelioid type. However, the present desmoplastic MPM case showed mild FDG uptake because of rich fibrosis.