Following is true about pleomorphic adenoma except –
**Core Concept**
Pleomorphic adenoma, also known as benign mixed tumor, is a type of salivary gland tumor characterized by its diverse cellular composition and potential for malignant transformation. It is the most common type of salivary gland tumor, predominantly occurring in the parotid gland.
**Why the Correct Answer is Right**
Pleomorphic adenomas are typically slow-growing, painless tumors that may present as a facial mass. They contain a mixture of epithelial and mesenchymal components, including myoepithelial cells, fibrous stroma, and glandular elements. The tumor's pleomorphic nature makes it difficult to diagnose histologically, often requiring immunohistochemical analysis for accurate identification.
**Why Each Wrong Option is Incorrect**
**Option A:** Malignant transformation of pleomorphic adenoma is a known but rare complication, occurring in approximately 10-15% of cases. The transformation can occur through a process called carcinomatous transformation, where the myoepithelial cells acquire malignant characteristics.
**Option B:** The most common location for pleomorphic adenoma is indeed the parotid gland, accounting for approximately 60-70% of all cases. However, they can also occur in the submandibular gland and minor salivary glands.
**Option C:** The tumor's growth pattern is typically slow and benign, but it can become locally aggressive and displace surrounding tissues.
**Clinical Pearl / High-Yield Fact**
It is essential to differentiate pleomorphic adenoma from other salivary gland tumors, such as Warthin's tumor and basal cell adenoma, which can present similarly. The clinical and histological features, combined with immunohistochemical analysis, can aid in accurate diagnosis.
**Correct Answer: A. Malignant transformation of pleomorphic adenoma is a rare complication.**