INTRODUCTION: Pleomorphic adenomas (PA) are the most common histologic type of salivary gland tumors. Malignant transformation may occur in the setting of recurrent or longstanding disease. OBJECTIVE: Evaluate the clinicopathologic characteristics of PA of the major salivary glands, particularly tumors showing signs of malignant transformation. MATERIAL AND METHODS: The clinical and histopathologic characteristics of 106 cases of PA were evaluated retrospectively. RESULTS: The mean patient age was 39.5 years. There was a predominance of female patients (69.5%). The parotid was the most commonly affected gland (86.8%). The tumor had been present for over a year in 76.74% of the cases, with a mean size of 3.48 cm. Histologic examination revealed a thin and incomplete capsule in 49% of the cases; however, protrusions into the capsule or extracapsular extension were infrequent (11.32% and 8.49%, respectively). The extracellular matrix varied from myxochondroid (41.5%), myxoid (36.8%), chondroid (3.8%) and fibrotic (1.9%); coexisting patterns were observed. The myoepithelial-epithelial component corresponded to 50% or more of the tumor in 65.1% of the cases, and was solid (40.6%), cystic (20.7%), arranged in cords (86.8%), ducts (81.1%) and had a palisading configuration (8.49%). Squamous metaplasia was present in 16.04% of the cases. Features associated with malignant transformation were incommon: extensive hyalinization (4,7%) and necrosis (0,9%). CONCLUSION: The histopathologic diversity of PA was confirmed. Features associated to malignant transformation were unfrequent.
Pleomorphic adenoma; Pathology; Major salivary glands; Malignant transformation
