Magnetic resonance imaging of myoepithelioma in the salivary glands

Myoepithelioma is a rare benign tumor composed of cells showing myoepithelial differentiation and accounts for only 1.5 % of all tumors in the major and minor salivary glands. Herein, we report the magnetic resonance imaging (MRI) findings, including dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI), of two cases of myoepithelioma occurring in the salivary glands of the floor of the mouth and the hard palate. Both tumors were seen as well-defined ovoid masses with low or intermediate signal intensity on T1-weighted images, and inhomogeneous high signal intensity areas on T2-weighted images, whereas inhomogeneous enhancement was seen on post-contrast T1-weighted images. On DCE-MRI, both tumors showed a time–intensity curve of early enhancement and a low washout pattern (plateau enhancement pattern). Their apparent diffusion coefficients measured on DW-MRI were both relatively low (1.12 × 10 −3 and 0.76 × 10 −3 mm 2 /s). The findings for these two myoepitheliomas on DCE-MRI and DW-MRI were dissimilar to those in previous reports.