Advanced Dental Admission Test (ADAT)

Which structure is typically found in pleomorphic adenomas?

1. Calcified inclusions

2. Neoplastic keratinocytes

3. Double-layered ducts

4. Necrotic tissue

The correct answer is: Double-layered ducts

Pleomorphic adenomas, commonly known as benign mixed tumors, are characterized by a specific histological architecture that includes both epithelial and mesenchymal components. One of the hallmark features of pleomorphic adenomas is the presence of double-layered ducts, which consist of an inner layer of cuboidal or columnar epithelial cells surrounded by an outer layer of myoepithelial cells. This dual-layer structure is indicative of the glandular differentiation typical of these tumors. The significance of the double-layered ducts lies in their role as a distinguishing feature of pleomorphic adenomas, helping pathologists identify these tumors under the microscope. This characteristic structure reflects the tumor's origin from salivary gland tissue, making it a key element in diagnosing this type of adenoma. The presence of such ducts is combined with a stroma that can vary from myxoid to chondroid, adding to the pleomorphic nature of the tumor. In contrast, other options such as calcified inclusions, neoplastic keratinocytes, and necrotic tissue do not represent the typical features of pleomorphic adenomas. While calcified inclusions may be present in some types of tumors, they are not a defining feature of pleomorphic adenomas. Similarly, neoplastic