Extragastrointestinal stromal tumour (EGIST) presented as a mesenteric and retroperitoneal mass

Abstract

Extragastrointestinal stromal tumour (EGIST) occurs outside the gastrointestinal tract and has histopathological and molecular characteristics similar to gastrointestinal stromal tumour (GIST). This tumour is rare and aggressive. A male patient was admitted with anaemia and lower limb oedema. CT scan showed a tumour in the mesentery and retroperitoneum, suspected to be a small bowel GIST. During laparotomy an unresectable mass was found compressing the retroperitoneal structures. Pathology and immunohistochemistry (CD117) confirmed an EGIST. EGIST arises from Cajal-like cells or from pluripotent stem cells outside the gastrointestinal tract. It is aggressive and has a worse prognosis than GIST. Immunohistochemistry is crucial for diagnosis. Surgery aimed at debulking as much of a tumour mass as possible is the cornerstone of treatment. The role of imatinib is not clear. EGIST is rare and has a bad prognosis, and there is no consensus on grading and management. A low threshold of suspicion is crucial for early diagnosis.

Retroperitoneal gastrointestinal stromal tumor: A case report and literature review

“…GISTs are the most common mesenchymal tumors of GI tract, accounting for approximately 1% of all GI malignancies [8 , 9] . The term EGIST was first named by Reith et al in 2000, describing all tumors that raised outside the GI tract sharing similar clinical presentation, imaging, histopathological, and molecular features with GISTs [10] .…”

“…The term EGIST was first named by Reith et al in 2000, describing all tumors that raised outside the GI tract sharing similar clinical presentation, imaging, histopathological, and molecular features with GISTs [10] . EGISTs are composed of 3 subtypes with retroperitoneal EGISTs is the rarest among them [ 4 , 8 ]. They are predominantly found in adults, ranging from 50 and 60 years old [11] .…”

“…Differential diagnosis between EGISTs and other types of tumors, for instance, lymphoma, leiomyoma, leiomyosarcoma, fibrosarcoma… is problematic because of their overlapped appearance [8 , 11] . Differential diagnosis also includes finding the primary site of GISTs.…”

“…To our knowledge, retroperitoneal EGISTs are considered rare, with only 60 cases reported in the English literature. Therefore, clinical findings, imaging characteristics, and management for this type of tumor have not been totally elucidated [8] . Computed tomography plays an important role in the detection and diagnosis of GISTs, evaluation of adjacent structure invasion, local and distal metastasis… MRI, with characteristics of high soft tissue contrast and multiplanar reconstruction, is becoming popular in the use of determining the primary site of large tumors and finding the relationship between the mass and major blood vessels, as well as surrounding organs [9] .…”

“…Computed tomography plays an important role in the detection and diagnosis of GISTs, evaluation of adjacent structure invasion, local and distal metastasis… MRI, with characteristics of high soft tissue contrast and multiplanar reconstruction, is becoming popular in the use of determining the primary site of large tumors and finding the relationship between the mass and major blood vessels, as well as surrounding organs [9] . However, due to their irregularity and absence of typical features, the definitive diagnosis can only be confirmed after biopsy or surgery, with positive result from immunohistochemistry of c-KIT (CD 117), a tyrosine kinase growth factor receptor [7 , 8] .…”