Pleomorphic Adenoma : Molecular Genetics
Approximately 70% of pleomorphic adenomas show cytogenetic abnormalities. 8q12 rearrangements (target gene: PLAG1 (pleomorphic adenoma gene 1) and 12q13-15 rearrangements (target gene: HMGA2 (high mobility group AT hook 2) ) are most common aberrations encountered in pleomorphic adenoma; sporadic cases may be seen without these abnormalities. Mutations in TP53 or overexpression of p53 is rarely seen in pleomorphic adenoma, whereas they are frequently encountered in malignant mixed tumor. This image depicts the classic appearance of pleomorphic adenoma with admixture of all three components – epithelial, myoepithelial and stromal components.