Objective: To assess the frequency of loss of expression of succinate dehydrogenase-B (SDH-B) in gastrointestinal stromal tumors (GISTS) of our population through immunohistochemistry.
Study Design: Descriptive study.
Place and Duration of Study: Department of Pathology, Shaukat Khanum Hospital & Research Centre, Lahore for a duration of 6 months, Apr 2015 to Sep 2015.
Patients and Methods: A total of 63 diagnosed cases of GISTS suitable by inclusion criteria were included in the study. The blocks of already diagnosed cases was reviewed by 2 pathologists and after confirmation SDH-B immunohistochemical stain was applied with normal tissue as its control. Lack of staining in tumor was interpreted as “Loss of expression”.
Results: Mean age of our population was n=44.83 ± 17.76 years. The most common tumor site was small intestine n=23 (63.5%) cases, followed by stomach, n=15 cases. CD117 was positive in all the tumors. Only n=3 tumors were found to be SDH-B deficient. All of these tumors involved the stomach and had a median age of 20 years. All of these tumors had an epithelioid morphology.
Conclusion: Immunohistochemistry was found reliable and cost-effective method for detecting mutation in SDH gene. Based on findings of this study it is recommended that all gastric GISTs below the age of 30 years with epithelioid morphology should be tested for SDH deficiency.
Keywords : Gastrointestinal stromal tumors, Immunohistochemistry, SDH-B.