Warthin tumor of the parotid gland: MR-pathologic correlation.

PURPOSE To describe the MR appearance of Warthin tumor and correlate the images with pathologic sections.

METHODS MR studies of seven patients with Warthin tumors in the parotid gland were retrospectively reviewed; MR results were compared with pathologic specimens in five instances.

FINDINGS One patient had a bilateral tumor; another had three tumors in the right parotid gland and one in the left. Ten tumors showed well-defined borders; the other, which was accompanied by infection, had an indefinite border only at the upper pole. All had thin capsules not shown on MR. Four showed small lobulations at the margins. Fibrosis appeared as septa-like structures of low signal intensity in three cases. There were areas of hemorrhage with accumulation of hemosiderin in two cases. All tumors had low or intermediate T1-weighted signal intensity, four with high intensity areas of cysts containing cholesterol crystals. On T2W images, two tumors had homogeneously intermediate intensity; the other nine had mixed intensity. Areas of intermediate intensity were correlated with abundant epithelial tissues; focal high-intensity areas were correlated with cysts and/or areas of predominant lymphoid proliferation.

CONCLUSIONS MR findings such as bilaterality and/or multiplicity, well-defined margins, and predominantly intermediate signal intensity on T1W and T2W images with focal areas of high signal intensities on T1W images suggest Warthin tumor, but are not pathognomonic.