Pathological examinations of perianal tumors and evaluation of the role of the MAPK signalling pathway in the oncogenesis of the tumor

Objective: CD117- also known as c-KIT- is a tyrosine kinase receptor encoded by the c-KIT proto-oncogene. In human studies, a relationship between c-KIT receptor and carcinogenesis has been determined in tumors that develop under the influence of gonadal hormones such as prostate cancer. In canine malign breast tumor cases, a relationship between tumor subtype and c-KIT staining pattern has been detected. The expression of c-KİT is unknown in perianal tumors that are claimed to develop under the influence of androgenic hormones. Material and Methods: In this study, c-KIT expression in perianal tumor gland cases (totally 17) and MAPK signal pathway activation were evaluated by immunohistochemistry. Perianal tumors were evaluated and classified in the light of suggested histopathological and immunohistochemical evaluation criteria. Results: 29% of the cases were diagnosed as perianal adenoma, 12% as perianal epithelioma, 59% as perianal carcinoma. None of the examined cases showed reactivity with CAM5.2. Statistical analysis did not revealed any differences in c-KIT expression between perianal tumor subtypes. Cytoplasmic c-KIT immunoreactivity was detected in reserve / basoloid cells in all cases. Although the c-KIT staining pattern in hepatoid cells varied between cases, cytoplasmic c-KIT immunoreactivity was detected in all cases. Positive staining with p-ERK1 / 2 was determined in 3 of the cases. Conclusion: In this study, which is a preliminary study, the determination of abnormal (cytoplasmic) staining pattern in general of the cases and the tendency of membranous staining to decrease suggested that c-KIT has a role in perianal tumor development. It has been also suggested that cases expressing high levels of c-KIT may benefit from kinase inhibitors. Keywords: CAM5.2, Canine, c-KIT, Perianal tumor, p-ERK1/2.