Immunohistochemical expression of progesterone receptors in pleomorphic adenoma and adenoid cystic carcinoma

Background: The importance of hormone receptor status in diagnosis, prognosis and response to hormone therapy of breast cancer has already been proven.
Aim: Morphologic mimicry and similarity between salivary gland tumors and breast tumors led us to undertake an immunohistochemical evaluation on the expression of progesterone receptors (PRs) in pleomorphic adenoma (PA) and adenoid cystic carcinoma (ACC) of salivary glands.
Study and Design: We researched the role of PRs in tumorigenesis and hormone therapy of PA and ACC with immunohistochemistry and their expression in normal salivary glands was studied. Association of progesterone expression with grade 2 and 3 ACC was researched.
Methods: In a descriptive, analytical, cross-sectional study, 29 paraffin blocks (14 samples of PA and 15 samples of ACC) were prepared for immunohistochemical staining with progesterone antibody. t-Test and Mann-Whitney test were used for the statistical analysis of the results.
Results: PR staining was negative in 15 ACC and 13 PA cases. Slight to moderate staining was seen around the tumor in 12 normal cases. Little or no PR staining was observed among endothelial cells, fibroblasts and inflammatory cells. No progesterone expression in grade 2 and 3 ACC in the salivary glands was observed.
Conclusion: Although progesterone seems to be essential for normal function of the salivary glands, it does not have a role in tumorigenesis and hormone therapy in PA and ACC. No association was found between progesterone expression and differentiation grade in ACC.