Abstract
BACKGROUND: Sessile serrated lesions (SSLs) are recognized as precursor lesions in the pathogenesis of colorectal cancer, particularly in the context of microsatellite instability (MSI). This study evaluates the role of immunohistochemical (IHC) markers in understanding the molecular and immunologic characteristics of SSLs. MATERIALS AND METHODS: A retrospective analysis was performed on 45 colonic neoplastic lesions diagnosed as SSLs. An IHC staining panel was conducted, including MLH1, p53, CD44, CD3, CD8, MUC2, MUC5AC, MUC6, chromogranin and Ki67 antibodies. RESULTS: MLH1 and p53 expressions showed correlations with dysplastic changes. Immunological markers CD3 and CD8 indicated a variable immune response, potentially reflecting the tumor's ability to evade immune surveillance in certain situations. CD44 was overexpressed in all SSLs. The number of neuroendocrine cells was overall reduced. CONCLUSIONS: SSLs are heterogeneous lesions, exhibiting a wide range of histological and molecular features. Using IHC might enhance diagnostic accuracy, particularly in lesions with ambiguous histological features, when dysplasia develops. Accurate identification of SSLs and understanding their molecular characteristics are crucial for assessing their malignant potential.