Role of Morphology and Immunohistochemistry in the Diagnosis of Incidental Cancers in Gallstone Disease

Abstract

Introduction: The majority of gallbladder adenocarcinomas have been known to develop from dysplasia or carcinoma in situ, without pre-existing adenomas, hence observation of these non-neoplastic or preneoplastic lesions is important as it may underlie an occult malignancy. To study the role of morphology and immunohistochemistry in the diagnosis of incidental cancers in cases of gall stone disease by adopting a universal histopathological screening policy for all the gallstone disease cases operated at our tertiary care center. Material and Methods: The present study was designed as an observational cross sectional study completed over a time period of 14 months. A total of 176 cases were included in the study including all the patients of gall stone disease in the adult age group. All the indeterminate and frankly malignant cases were subjected to immunohistochemistry with a panel of antibody markers including p53, CEA and Ki-67 using Streptavidin Biotin immunoperoxidase method Fisher-exact test was used to compare the data taking‘p’ value less than 0.05 as statistically significant. Results: Mean age of patients was 40.55±13.25 years. Majority of patients (n=141; 80.1%) were females. The final diagnosis revealed a dominance of non-neoplastic inflammatory (n=168; 95.5%) pathology. There were 8 (4.5%) of malignancy, of these 7 were adenocarcinoma and 1 was adenosquamous carcinoma. Atypia was seen in 5 (2.8%) cases and 3 (1.7%) cases were of dysplasia. Histopathology detected carcinoma in 7 (4%) cases whereas addition of immunohistochemistry helped to find out one more unidentified case, thus the diagnostic yield increased to 8 (4.5%) cases. Out of three dysplasia cases, one (33.3%) was found positive on immunohistochemistry, which was later confirmed to be malignant. None of the cases of atypia were positive on p53, Ki-67 and CEA immunohistochemistry. On comparison between the three groups, the results were statistically significant (p=0.00062). Conclusion: Immunohistochemistry has a useful role in detection of incidental gallbladder carcinoma when morphology is limited by indeterminate results. A panel of immunohistochemical markers including p53, Ki-67 and CEA may prove very useful to pick up cases of malignancy in such cases of diagnostic dilemma.