# Differentiating Neoplastic From Non-neoplastic Gallbladder Lesions Using MUC1 and MUC5AC: An Immunohistochemical Analysis

## TL;DR

This study shows that MUC1 and MUC5AC proteins can help distinguish cancerous from non-cancerous gallbladder lesions using immunohistochemistry.

## Contribution

The study identifies MUC1 and MUC5AC as effective immunohistochemical markers for differentiating neoplastic from non-neoplastic gallbladder lesions.

## Key findings

- MUC1 showed significantly higher expression in neoplastic lesions compared to non-neoplastic ones.
- MUC5AC was predominantly expressed in non-neoplastic lesions and had lower expression in neoplastic cases.
- Combining MUC1 and MUC5AC expression improved diagnostic accuracy for gallbladder lesions.

## Abstract

Background: Gallbladder lesions range from benign inflammatory conditions to malignancies, often progressing through pre-neoplastic stages. Accurate histopathological differentiation, particularly in early stages, remains challenging. Mucin proteins MUC1 and MUC5AC have emerged as potential immunohistochemical (IHC) markers for distinguishing neoplastic from non-neoplastic gallbladder pathology.

Material and methods: A cross-sectional study was conducted on 52 formalin-fixed, paraffin-embedded (FFPE) gallbladder specimens from cholecystectomy cases over two years. Routine histopathological evaluation was followed by IHC staining using monoclonal antibodies against MUC1 and MUC5AC. Expression levels were semi-quantitatively scored (0-3) and statistically analyzed in relation to neoplastic status.

Results: Of the 52 cases, 29 (55.8%) were non-neoplastic and 23 (44.2%) were neoplastic, with 91.3% (n = 21) of the latter being malignant. MUC1 expression was significantly higher in neoplastic lesions (p < 0.001), with 73.9% (n = 17) showing strong (score 3) positivity. Conversely, MUC5AC was predominantly expressed in non-neoplastic lesions, with strong expression observed in 55.2% (n = 16) versus 13.0% (n = 3) of neoplastic cases (p < 0.001). MUC1 demonstrated high diagnostic performance for neoplasia (sensitivity 95.7%, specificity 75.9%), while MUC5AC showed moderate performance (sensitivity 69.6%, specificity 72.4%). The inverse expression profiles of these markers effectively differentiated malignant from benign lesions.

Conclusion: MUC1 and MUC5AC exhibit distinct IHC expression patterns in gallbladder pathology. MUC1 is a sensitive marker for neoplastic transformation, whereas MUC5AC is more indicative of benign or early-stage lesions. Their combined application may improve diagnostic accuracy in histologically ambiguous cases. Incorporating these biomarkers into routine pathology practice may aid early detection and better clinical decision-making. Further large-scale studies are needed to validate their prognostic significance.