ABSTRACT
Purpose: To differentiate pleomorphic adenoma from histologic mimics by assessing the             expression of GFAP in salivary gland tumors.
Study design: A Cross-sectional study
Place and duration of study: This study was conducted in the Department of Histopathology/ Oral Pathology at The Armed Forces Institute of Pathology Rawalpindi from 15^th July 2024 to 31^st March 2025.
Material and Methods: Forty-six biopsy specimens; 23 of pleomorphic adenoma, 3 of epithelial myoepithelial carcinoma, 7 of adenoid cystic carcinoma, 4 of acinic cell carcinoma, 6 of mucoepidermoid carcinoma, and 3 specimens of salivary duct carcinoma were stained with Glial fibrillary acidic protein. For preliminary diagnosis Hematoxylin and Eosin stains were used and expression of the immunohistochemical protein were recorded by the observer for interpretation.
Results: Glial fibrillary acidic protein showed statistically significant positivity in pleomorphic adenomas by strong diffuse positive expression in the myoepithelial cells as well as in the stroma in some cases. However, the expression of this marker in other malignant salivary gland tumors was absent.
Conclusion: The use of Glial fibrillary acidic protein can be helpful in distinguishing pleomorphic adenoma from other malignant salivary gland tumors that can be confused with pleomorphic adenoma on the basis of histopathology. It can specially be useful in routine limited biopsy materials such as core needle biopsies where diagnosis becomes a dilemma.
Key Words: Pleomorphic Adenoma, Glial Fibrillary Acid Proteins, Histological Mimics, Salivary Gland Tumors