Medical-type peritoneal mesothelioma leading to death two months after onset of fever of unknown origin

In malignant mesotheliomas, cases involving the peritoneum as the primary site are rare, accounting for approximately 10% of all mesothelioma cases. We report a case of medical-type peritoneal mesothelioma leading to death 2 months after the onset of fever of unknown origin, along with a review of the literature. A 76-year-old man presented with a fever of unknown origin over 4 weeks. Thoracoabdominal computed tomography (CT) scan showed increased mesenteric adipose tissue density. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan showed diffuse hyperaccumulation in the mesentery and hyperaccumulation in the intraperitoneal and parasternal lymph nodes. A thoracoscopic biopsy of the parasternal lymph nodes revealed metastatic peritoneal mesothelioma. The treatment plan was discussed with him and his family, and the best supportive care was provided. 2 months later, he died from multiple organ failure. Underlying malignant tumors cause 38% of mesenteric panniculitis cases. Symptoms accompanied by lymphadenopathy within the area of mesenteric panniculitis are highly suggestive of malignancy. Peritoneal mesothelioma can be classified as (1) classical, which is accompanied by abdominal pain, ascites, and abdominal masses; (2) surgical, which is accompanied by hernia incarceration and intestinal occlusion; and (3) medical, wherein systemic symptoms, such as fever and weight loss, are primarily observed. The medical-type peritoneal mesothelioma, wherein systemic symptoms are primarily observed, has a poorer prognosis than the other types. FDG-PET/CT is an effective diagnostic modality for peritoneal mesothelioma and typically shows diffuse hyperaccumulation along the peritoneal surface.