What feature of pleomorphic adenoma makes it a concern for recurrence?

The concern for recurrence in pleomorphic adenoma is primarily associated with its potential for malignant transformation. Pleomorphic adenoma, also known as a benign mixed tumor, is characterized by a mixture of epithelial and mesenchymal components, which can vary in appearance. Although the tumor itself is classified as benign, if not completely excised, residual tumor cells can remain, leading to regrowth and recurrence.

Malignant transformation can occur in cases where the tumor is left untreated for extended periods, typically around 15 years or more. If a pleomorphic adenoma undergoes malignant transformation, it may evolve into a salivary gland carcinoma, which poses significant risks for the patient and complicates treatment. Therefore, the potential for malignant transformation highlights the importance of complete surgical excision to minimize the risk of recurrence and progression to a more severe form of the disease.

Other factors, like tumor location, size, and histological variability, may contribute to management considerations and surgical challenges but are not as directly linked to the risk of recurrence compared to the potential for malignant transformation. This is why the feature of malignant transformation is regarded as a critical concern when assessing pleomorphic adenomas.