Abstract
A 64-year-old man presented with a chief complaint of lower right abdominal pain. Abdominal ultrasonography and contrast-enhanced CT showed a hepatic mass with a diameter of 3 cm in contact with the diaphragm. Lower gastrointestinal endoscopy revealed cancer progression in the sigmoid colon, and he was preoperatively diagnosed with simultaneous liver metastasis. Laparotomy revealed the principal site of the mass was in the diaphragm, being fed from the right inferior phrenic artery. The mass was firmly attached to the liver, and the patient underwent a complicating partial diaphragm resection, sigmoid colectomy, and D3 lymph node dissection. Immunostaining of the diaphragm mass showed negative results for carcinoembryonic antigen (CEA), hepatocytes, and thyroid transcription factor (TTF)-1, but positive findings for cytokeratin 5/6 (CK5/6), epithelial membrane antigen (EMA), D-2-40, and calretinin, and the patient was ultimately diagnosed with peritoneal mesothelioma. Localized peritoneal mesothelioma is a hypervascular tumor, and identification of feeding vessels with contrast angiography or CT angiography is regarded as an auxiliary method of diagnosis. This case suggests the possibility that serum CA125 levels and CA125 immunostaining might offer auxiliary diagnostic methods or indicators of recurrence.
