Clinicopathologic and immunohistochemical study of gastrointestinal stromal tumor (ten cases) and extragastrointestinal stromal tumor (six cases) with review of literature

Abstract

Aims: The diagnosis of gastrointestinal stromal tumor (GIST) and extragastrointestinal stromal tumor (EGIST) depends on both characteristic histopathology (HP) and immunohistochemistry. The aim of the present study is to study the clinicopathological and immunohistochemical features of these tumors. Materials and Methods: This is a 6-year (2009–2015) retrospective study conducted in a tertiary care center. It includes all the cases of GIST and EGIST diagnosed in that period. Clinical records and HP slides of all cases were reviewed. Appropriate tissue blocks were selected for making a manual tissue microarray. Using the microarray, immunostaining for CD117, discovered on GIST-1 (DOG-1), S-100, desmin, smooth muscle actin, CD34, and vimentin was performed. Results: GISTs (total 10 with 3 low-risk, 4 intermediate-risk, and 3 high-risk type) were abdominal masses located commonly in the small intestines of adult men (mean age 52 years). EGISTs (6 cases all high-risk type) were larger abdominal masses affecting younger patients (mean age 50 years) located in the mesentery and retroperitoneum. All GIST and EGIST showed Cd117 and vimentin positivity. DOG-1 clone 1.1 was positive in 6 of 7 GIST (85.7%) and 2 of 3 EGIST (66.6%). Immunoreactivity for DOG-1 clone K9 was observed in 2 of 7 GIST (28.5%) and in 1 of 3 EGIST (33.3%). Conclusion: This study reaffirms the importance of CD117 in diagnosis of GIST and EGIST. Of the two clones of DOG-1 used, clone1.1 is a more sensitive marker.