Histopathological findings of pleomorphic adenomas of the salivary glands

Objectives: To describe the histopathological features of pleomorphic adenoma (PA) with special reference to the epithelial and mesenchymal components. Study design: 189 PA were selected and classified as myxoid or stroma-rich, cellular or cell-rich and classic (balanced amount of epithelial and stromal components). The epithelial component was analyzed according to the presence of plasmacytoid, spindle, clear, squamous, basaloid, cubic, oncocytoid and mucous cells and the morphological pattern (trabecular, ductal, cystic and solid). The stromal component was analyzed according to the presence of myxoid, hyaline, chondroid or calcified tissue. Results: Plasmacytoid cells were the most commonly found cellular type followed by fusiform and cuboidal cells. Trabeculae and duct-like structures were the most frequent patterns formed by the epithelial cells. Myxoid and chondroid stroma were the most frequently found mesenchymal-like tissue usually forming the so called myxochondroid stroma. Conclusion: The knowledge of the immense variety of cells, architectures and morphological characteristics present in PA of the salivary gland is essential for a correct diagnosis.