Abstract
A 71-year-old man had been diagnosed with sigmoid colon cancer by colonoscopy during a close inspection of anemia. Computed tomography (CT) showed no tumor and ascites like a dissemination, so we performed a laparoscopic sigmoidectomy with a diagnosis of sigmoid colon cancer at clinical stage II. In operative findings, many small white nodules were detected in the peritoneum, we suspected dissemination of sigomoid colon cancer and performed only the sigmoidectomy with enucleation of part of the nodules for diagnosis. The pathological diagnosis of the nodule was well-differentiated papillary mesothelioma (WDPM) and mFOLFOX6 was administered as adjuvant chemotherapy for sigmoid colon cancer at stage III a. WDPM is a rare low grade malignant subtype of peritoneal mesothelioma and often shown in women. Because of its slow growth, most patients have good progression. But we considered that intensive followup was needed in this patient because WDPM rarely converts to high grade malignancy.
