Gastrointestinal and Extra-Gastrointestinal Stromal Tumours: A Clinicopathological and Immunohistochemical (c-KIT) Study

Abstract

Introduction: Gastrointestinal Stromal Tumour (GIST) is one of the most common mesenchymal tumours of GIT. They have been proved to be arising from the smooth muscle pacemaker interstitial cells of Cajal, these cells are involved in gut motility and peristaltic movements. They can also rarely arise outside the Gastrointestinal Tract (GIT) from retroperitoneum, mesentery and omentum called as Extragastrointestinal Stromal Tumor (EGIST). Single best defining feature of GIST is positivity for Cytoplasmic Tyrosine Kinase (c-KIT). Aim: The aim of the study was to analyse clinicopathological features and c-KIT expression in both gastrointestinal and EGISTs. Materials and Methods: This was a retrospective observational (cohort) study; over a period of two years from January 2018 to December 2019, done at Navodaya Medical College and Hospital, Raichur, Karnataka, which comprised of 12 cases of GIST. All the cases were a resected specimens and thorough evaluation of clinical, imaging and histopathological studies were done and forwarded for immunohistochemistry for c-KIT expression. Results: Age of cases ranged from 04-70 years, mean age being 50.6 years and male to female ratio 2:1. Presenting symptoms of most of GIST were pain abdomen, diarrhea and few with vomiting whereas, rectosigmoid GISTs (2 cases and one with metastasis to liver) were associated with pain abdomen, bleeding per rectum and constipation. One case of retroperitoneal (extraintestinal) GIST was asymptomatic and other presented with pain in the right hip due to secondaries and one benign gastric serosal GIST was associated with gastric adenocarcinoma. The CT scan in two of malignant GISTs, confirmed metastasis and c-KIT study was negative in these 2 malignant GISTs. Conclusion: This study reaffirms importance of CD117 in diagnosis of GIST and EGIST, however, the negativity of CD117 does not rule out GIST, which requires thorough clinico-radiological and pathological correlation.