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

Abstract

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.

Keywords: Desmoid tumor; Gastrointestinal stromal tumor; Recurrence; Retroperitoneum; Surgery.

Figure 1

Abdominal computed tomography images and pathologic features of gastrointestinal stromal tumor, metastatic hepatic gastrointestinal stromal tumor and retroperitoneal desmoid tumor. A: Abdominal computed tomography (CT) scan reveals a 10-cm tumor (arrow) located at the greater curvature of the stomach; B: The excised specimen discloses a patch of gastric mucosa with a central deep-seated ulcer and the gastrointestinal stromal tumor adhering to the red yellow omental tissues; C: Histologically, the 10-cm gastric tumor demonstrated sheets of CD117-positive epithelioid cells after immunohistochemical (IHC) staining (right lower inset), hematoxylin and eosin (HE) stain, ×200; D: The follow-up abdominal CT scan shows metastatic tumors in the liver (left lower arrow) and upper greater curvature of the stomach (right upper arrow); E: The histology of metastatic liver tumor demonstrated nests and sheets of CD117-positive epithelioid tumor cells (right lower inset, IHC stain). Entrapped hepatocytes are seen in the middle lower portion, HE stain, ×200; F: Abdominal CT scan discloses a tumor neogrowth (arrow) located in the retroperitoneum between the pancreatic tail and splenic hilar region; G: Histologically, the retroperitoneal tumor demonstrated proliferative spindle cells with keloid-like bundles and erythrocyte extravasation, HE stain, ×200. IHC staining reveals a positive nuclear beta-catenin in spindle cells (right lower inset).