[Resection of a Desmoid Tumor Originating from the Greater Omentum after Surgery for Colon Cancer and Liver Metastasis-A Case Report].

Here, we report the case of a 66-year-old male patient who previously underwent resection of sigmoid colon cancer and its liver metastasis. His follow-up contrast-enhanced CT scan revealed a mass shadow at around the gastrosplenic ligament, which gradually increased in size. Because it could not be pathologically diagnosed by transgastric EUS-FNA, en bloc resection wasperformed surgically for the tumor in the greater omentum. Hematoxylin-eosin staining of the resected specimen showed fibroblast-like cellswith hyperplasia of bold collagen fibersand spindle-shaped nucleus. While the immunostaining findings denied a diagnosis of mesenchymal neoplasm such as GIST, leiomyosarcoma, or schwannoma, it was pathologically diagnosed as a desmoid tumor. He has been followed up without any recurrence for 2-and-a-half years after the surgical resection. Desmoid tumors tend to be locally invasive; thus, there is the potential for local recurrence, although the frequency of distant metastasis is very low. In cases in which the tumor increases in size, en bloc resection with sufficient surgical margin should be performed. Cases of desmoid tumors originating from the greater omentum are reportedly rare; however, en bloc resection may be useful for both diagnosis and treatment of tumors of the greater omentum showing increased size that are also surgically resectable.