Clinico-Histomorphological Spectrum and CD34 in Gastro-Intestinal Stromal Tumours: An Experience from Tertiary Care Centre, Kolkata, India

Abstract

Introduction: Gastrointestinal Stromal Tumours (GISTs) are an important subcategory of mesenchymal tumours of gastrointestinal tract. The discovery of c-kit mutation in a subset of GIST has made amenable the treatment of this entity by targeted therapy. Although, Cluster of Differentiation 34 (CD34) is a well established marker aiding in diagnosis of GIST, recent development of novel markers like Discovered on GIST1 (DOG1), CD117 have undermined its value. Still it’s a frequently used marker in the resource poor settings. Aim: To study the expression of CD34 immunomarker with respect to site, grade, stage, histomorphological type and risk category of GIST specimens received in the stipulated time period. Materials and Methods: An observational retrospective crosssectional was conducted in the Department of Pathology at R G Kar Medical College and Hospital, Kolkata, West Bangal, India. The duration of the study was three years and 11 months, from September 1, 2019 to August 31, 2022. All the samples diagnosed as GISTs within the study period, were taken from the received specimens in the department and immunohistochemical examination was done on the selected samples using monoclonal antibodies against CD34 after obtaining thin sections from formalin fixed paraffin embedded blocks and retrieval of antigen. The data was interpreted by light microscopy using a semiquantitative method with respect to prefixed parameters, where 50% proportional positivity of CD34 in the tumour cells was considered as positive. The data was analysed using Statistical Package for Social Sciences (SPSS) version 25.0. Results: Mean age of the study participants was 49.78 years. A total of 8 (34.7%) cases originating from stomach and 13 (56.5%) from intestine. Eight out of 23 (34.7%) cases showed positive expression of the marker. Six out of eight cases of gastric GISTs were found to be positive and 66.6% cases of high grade GISTs were positive for CD34. Statistically significant association was found between expression of CD34 and the site of tumour;-GISTs arising from stomach, particularly of spindle cell type, showing strong expression (p=0.003). It was found that, high grade GISTs are more likely to be positive for CD34. None of the epithelioid GISTs have shown positivity, neither any significant association was evident between expression of this marker with tumour stage or risk category. Conclusion: GISTs arising from stomach, particularly of spindle cell type, are more likely to show strong CD34 expression. Higher grade GISTs were found to be associated with positive CD34 expression in the present study, but no significant association was evident between expression of this marker.