PET/CT Demonstration and Monitoring of Thoracic and Abdominal Wall Mesothelioma

Malignant Peritoneal Mesothelioma With Butterfly-Shaped Muscle Metastasis: 68Ga-FAPI PET/CT Versus 18F-FDG PET/CT

ABSTRACT

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.

A Case of Localized Malignant Peritoneal Mesothelioma Evaluated by 18F-FDG PET/CT

Localized malignant mesothelioma is rare. The prognosis is generally more favorable for this condition than for diffuse malignant mesothelioma. An elderly woman recently complained of abdominal pain, fever, and weight loss. She had no history of asbestos exposure. Her serum CEA level was elevated. Plain CT revealed a mass under the left diaphragm, with liquefaction and necrosis. A contrast-enhanced scan showed circular enhancement of the mass. A subsequent biopsy of the mass revealed a poorly differentiated carcinoma. PET/CT showed a significant FDG-avid subphrenic mass without any indications of metastasis. Postoperative pathological and immunohistochemical examination confirmed a case of malignant mesothelioma.

Abdominal Wall Granulomatous Inflammation Mimicking Malignancy on FDG PET/CT

An old woman with abdominal pain complained a palpable mass on the right anterior abdominal wall. On PET/CT images, the lesion presented as a soft tissue mass with irregular shape, invading adjacent peritoneum and showing intense FDG uptake. Based on imaging findings, a malignancy was suspected, and she underwent surgical resection. However, the abdominal wall mass was diagnosed as granulomatous inflammation with a little necrosis by pathological results. Awareness of this benign disease is helpful for an accurate diagnosis of abdominal wall mass.

Serendipitous discovery of peritoneal mesothelioma

We present the case of a 64-year-old patient with a history of Birt-Hogg-Dube syndrome, polycystic kidney disease treated with renal transplantation in May 2013, and multiple types of skin cancers, including malignant melanoma. He presented for lymphoscintigraphy for sentinel lymph node identification of the melanoma. Subsequent biopsy of the right axillary sentinel lymph node yielded a diagnosis of epithelial type malignant mesothelioma without a known primary tumor. Follow-up positron emission tomography with 2-deoxy-2-(fluorine-18)fluoro-D-glucose integrated with computed tomography (F-18 FDG PET/CT) demonstrated several suspicious hypermetabolic abdominal masses that were later confirmed to be epithelial-type mesothelioma via percutaneous biopsy.