Postoperative retroperitoneal desmoid tumor mimics recurrent gastrointestinal stromal tumor: a case report

Desmoid tumor is a locally invasive, myofibroblastic, nonmetastatic tumor. Its pathogenesis remains unclear and it may involve genetic abnormalities, sex hormones and traumatic injury, including surgery. Postoperative intra-abdominal desmoid tumor is rare, especially in the retroperitoneum. We report a case of postoperative retroperitoneal desmoid tumor that developed 29 mo after the first excision of a gastrointestinal stromal tumor. Sporadic trauma-related intra-abdominal desmoid tumors reported in the English literature are also reviewed. Despite an extremely low incidence, postoperative desmoid tumor should be considered in the differential diagnosis when a recurrent neoplasm is found at least one year after operation. However, it is a clinical challenge to distinguish recurrent malignant neoplasms from desmoid tumors, and surgical resection is the treatment option depending on the anatomic location.