Immunohistochemical Expression of MUC5AC in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (SCC) is the most common oral malignancy, representing up to 80-90% of all malignant neoplasms of the oral cavity. High-grade mucoepidermoid carcinoma (MEC) can share histological similarities with SCC, making their distinction challenging. SCC is characterized by frank anaplasia and evident keratinization, serving as distinguishing features from high-grade MEC. However, in incisional biopsies lacking these characteristics, differentiation becomes problematic, as immunohistochemical findings tend to be similar. Literature indicates that MUC5AC is present in MEC but notably absent in SCC. Thus, this study aims to evaluate MUC5AC expression in both OSCC and MEC and its role as a diagnostic immunomarker for these two entities. A comprehensive literature review revealed a scarcity of studies investigating MUC5AC expression in OSCC. Therefore, the current study seeks to investigate the immunoexpression of MUC5AC in OSCC and compare it with MEC. This study includes total of 40 cases, 20 cases of OSCC and 20 cases of MEC. Immunohistochemical analysis was performed to assess MUC5AC expression. The intensity and localization of immunoexpression were assessed in all cases. 95% MECs cases were immunopositive for MUC5AC. Moderate to strong cytoplasmic immunoreactivity for MUC5AC was noted, particularly in mucous cells present within the tissue section. In contrast, none of the 20 OSCC cases exhibited immunopositivity for MUC5AC. MUC5AC expression was predominantly confined to MEC, suggesting its potential utility as a biomarker for distinguishing between OSCC and MEC in differential diagnoses.