Malignant Peritoneal Mesothelioma With Butterfly-Shaped Muscle Metastasis

Malignant peritoneal mesothelioma is a rare malignancy that may manifest as extraperitoneal metastasis. We describe the findings of 68 Ga-FAPI and 18 F-FDG PET/CT in a case of malignant peritoneal mesothelioma with widespread muscle metastasis in a butterfly-shaped distribution pattern. We found that FDG and FAPI uptake in the peritoneal tumor and its spread were inhomogeneous. Notably, 68 Ga-FAPI PET/CT more clearly showed relevant lesions compared with 18 F-FDG PET/CT.