Localized multiple malignant epithelioid peritoneal mesotheliomas arising from the hepatoduodenal ligament and diaphragm: a case report

BACKGROUND: Malignant peritoneal mesothelioma is a rare aggressive tumor of the peritoneum. We report a rare case of resection of multiple localized malignant peritoneal mesotheliomas. CASE PRESENTATION: A 55-year-old Japanese woman was admitted to our hospital because liver tumors were detected by abdominal ultrasonography during a screening examination. Blood examination findings, including tumor makers, were within normal ranges. She had no evidence of exposure to asbestos. Computed tomography showed four hypervascular, round liver tumors, one in the lateral liver segment adjacent to the hepatic hilus, and the other three on the liver surface. Computed tomography angiography revealed that the tumor in the lateral segment had strong enhancement and was fed from the left gastric artery. In contrast, the other tumors showed no enhancement, and were fed from the right inferior phrenic artery. Abnormal accumulation was identified in the four tumors only with (18)F-fluorodeoxyglucose positron emission tomography. It was very difficult to obtain a definitive preoperative diagnosis, but surgical resection was performed because we considered potential malignancy. Laparotomy revealed the principal site of the tumor in the lateral segment was on the hepatoduodenal ligament, and all other tumors were on the diaphragm. A left lobectomy and partial diaphragmatic resection were performed. The final pathological diagnosis was multiple malignant epithelioid mesotheliomas. Our patient has had no recurrence for 20 months postoperatively. CONCLUSIONS: In general, malignant peritoneal mesotheliomas are classified as diffuse tumors, which are often unresectable and have a poor prognosis. However, early diagnosis and treatment, particularly with the localized type, as in our patient, could lead to long-term survival of the patient. We recommend that multiple malignant epithelioid mesotheliomas be included in the differential diagnosis for patients with subcapsular hepatic tumors.