Immunohistochemical Expression of Stromal Variety of Pleomorphic Adenoma

Objectives: To conduct a histochemical and immunohistochemical analysis of PA’s stromal variety.
Methods: Five PA were select from the Oral Pathology Laboratory at the National School of Dentistry, National University of Mexico (UNAM). Histological sections for H&E, safranin O and alcian blue for glycosaminoglycans and the COL II, COL XI, SMA, Vim, Sox9 and aggrecan antibodies were performed. The proportion of positive cells assessed semiquantitatively and optical units (OU) via software ImageJ was determined.
Results: PA stained with H&E exhibited: chondro-myxoid stroma showed (3), myxoid stroma (1) and fibrous stroma (1). All were diffusely positive for Alcian Blue, while Safranin was positive in chondro-myxoid areas (3) and fiber (2). Vimentin, SMA and aggrecan strongly expressed in plasmacytoid type myoepithelial cells, fusiform cells and scale-like cells. Chondroid and myxoid stroma were slightly positive for aggrecan. COL II and XI were positive in the myoepithelial cells, regardless of their location and morphology. Nevertheless, COL II was negative in epithelioid cells and COL XI was positive in epithelioid cells. Sox9 strongly expressed in the cytoplasm of epithelioid morphology, faded in stromal areas and expressed in peripheral lacunar cells, thus suggesting with the mesenchymal phenotype.
The different morphologies of neoplastic myoepithelium (epithelioid, fusiform, plasmaciotide and scale-like cells) secreted proteoglycan (aggrecan), thus favoring deposition of Col II and XI on the chondroid stroma. As transition of epitelial cells into stroma was effect reduced SMA microfilament expressed was observed.
Conclusions: Sox9 possibly influences COL II and COL XI, favoring deposition of chondroid matrix. Aggrecan overexpression with the above proteins may indicate the role it plays in the possible formation of cartilage.