Ultrasonographic and sonoelastographic features of pleomorphic adenomas of the salivary glands.

Aims: The typical ultrasound features of pleomorphic adenomas are considered to be the well-defined contour, the regular, sometimes lobulated shape, homogeneous structure and poor vascularization. The goal of our study was to verify the validity of these features and to identify a typical sonoelastographic pattern for pleomorphic adenomas.

Patients And Methods: Between April 2007 and February 2010, 70 salivary gland masses were examined prospectively (58 in the parotid gland, 12 in the submandibular gland). The following features were targeted: size, limits, contour, structure, echogenicity, vascularization, elasticity/stiffness.

Results: Of the 70 tumors, 32 (45.7%) were pleomorphic adenomas, 12 (17.1%) Warthin tumors, 9 (12.8%) other benign tumors, 13 (18.5%) primary malignant tumors, 3 metastases from carcinoma, and 1 non-Hodgkin lymphoma. Among pleomorphic adenomas, 15 (46.9%) were inhomogeneous, 7 (21.9%) contained necrotic areas and 14 (43.7%) were well-vascularized. The lobulated contour was identified in 14 pleomorphic adenomas (43.7%), no other benign tumor presented this type of contour, but it was identified in 2 malignant tumors (15.3%). On sonoelastography, most pleomorphic adenomas were heterogeneous. The elastic component represented more than 50% of the tumor tissue in 22 cases (68.7%). This aspect was also identified for 6 malignant tumors (46.1%).

Conclusions: Our results demonstrate that features such as heterogeneous structure, rich vascularization and intra-tumoral necrosis may be identified in a significant number of pleomorphic adenomas. The most specific element in our group was the presence of a lobulated contour, which was not seen in any other benign tumor, but may rarely appear in certain malignant tumors. The elastographic aspect was heterogeneous for most tumors, but the elastic composition identified in most pleomorphic adenomas was also present in a significant proportion of malignant tumors. Therefore, a typical sonoelastographic pattern for pleomorphic adenomas could not be identified.