Intra-abdominal desmoid tumor after resection for gastrointestinal stromal tumor of the small intestine: case report.

Mesenchymal tumors are thought to constitute only 1% of primary gastrointestinal malignancies. Both gastrointestinal stromal tumor and desmoid tumor are rare. The case of a 56-year-old male with a desmoid tumor 1 year after surgical removal of a gastrointestinal stromal tumor near the ligament of Treitz is described. Although he received adjuvant therapy of imatinib mesylate for 1 year after the surgery, a small nodule was found 1 year and 3 months after the surgery. The nodule was considered to be a recurrent tumor of gastrointestinal stromal tumor, and a wedge resection of the duodenum including the tumor was done. Histopathological examination by immunohistochemical staining revealed that it was a desmoid tumor. It would be useful to be aware of the possibility of desmoid tumor after removal of gastrointestinal stromal tumor. To accumulate further information on these rare diseases, a central database that includes rare diseases will be necessary.