A case of localized malignant peritoneal mesothelioma

A 48-year-old man with abdominal pain was referred to our hospital after a circumscribed 5 cm abdominal tumor was detected by ultrasound examination at another hospital. Abdominal CT scan showed weakly and gradually enhanced tumor in the caudal side of the posterior segment of the liver. Furthermore, the tumor exhibited increased tumor uptake of FDG, with a standardized uptake value of 10.8 in PET/CT scan. All serum tumor markers, such as CEA, CA19-9, AFP, and PIVKA-II were within normal range. Surgical resection was performed for the tumor that was preoperatively considered as liver tumor or retroperitoneal malignant tumor or gastrointestinal stromal tumor in the differential diagnoses. The histopathological and immunohistochemical examination of the resected specimen showed the tumor to be malignant peritoneal mesothelioma, whereby cells were stained positively for calretinin, cytokeratin 5/6, D2-40 and AE1/AE2, negatively for CEA and cytokeratin 20. The postoperative course was uneventful. The patient has had no recurrence for 9 months after surgery.