Differentiation of pleomorphic adenoma and Warthin’s tumor of the parotid gland: ultrasonographic features

Abstract

Ultrasound imaging characteristics, including multiple occurrences, shape, intrinsic cystic change, and the grade and distribution of tumor vessels, can be used to differentiate pleomorphic adenomas from Warthin's tumors.

Vascular Pattern Analysis on Microvascular Sonography for Differentiation of Pleomorphic Adenomas and Warthin Tumors of Salivary Glands

“…We found no grayscale sonographic features of the tumors that were significantly different between the groups. The border characteristics of the tumors were not useful in distinguishing between the tumors in several earlier studies . In our study, most tumors showed well‐defined borders, and only 3 patients showed partially poorly defined borders.…”

“…Sonography is an effective method for detecting and localizing salivary gland tumors. However, even differentiating between the two most common salivary gland tumors, pleomorphic adenomas and Warthin tumors, is challenging on sonography …”

“…Grayscale sonographic evaluations of the tumors included the long and short diameters of the tumors, shape (ratio of the long diameter to short diameter), border characteristics (well defined [>90%] or presence of a poorly defined border), echogenicity (hypoechoic, isoechoic, or hyperechoic compared with the adjacent normal parenchyma of the salivary gland), heterogeneity (homogeneous or heterogeneous internal echo texture), and presence of cystic areas (no cystic change, partial cystic change [≤50%], or predominant cystic change [>50%]). The vascular patterns of the salivary gland tumors were evaluated in terms of vascular distributions (avascular, absence of flow signals within the tumors; central [internal], vascular signals in tumor masses; peripheral, vascular signals along the periphery of the tumors; or mixed, presence of both peripheral and central flow) and internal vascularity (grade 0, no visible tumor vessels; grade 1, consistent detection of 1 or 2 separate vessels; grade 2, consistent detection of 3–5 separate visible vessels; and grade 3, > 5 separate visible vessels; same grading system as in a previous study on both power Doppler and microvascular sonography based on the imaging planes that showed the largest axial diameters of the tumors (Figures ).…”

“…Even though these tumors are benign, preoperative knowledge of tumor pathology affects the treatment strategy, surgical procedure, and morbidity . Pleomorphic adenomas are associated with a 2% to 25% risk of malignant transformation over time, and recurrence rates have been shown to be higher in patients who undergo enucleation; therefore at least a partial parotidectomy should be performed . In contrast, Warthin tumors usually do not recur, and malignant transformation has not been observed .…”

“…Many previous studies have focused on differential diagnosis between pleomorphic adenomas and Warthin tumors using sonography. However, because of the substantial overlap in sonographic features between these tumors, including vascular features on Doppler sonography, results were inconsistent among studies …”