MRI findings of epithelial–myoepithelial carcinoma of the parotid gland with radiologic–pathologic correlation

Purpose This study aimed to describe the MRI findings of epithelial-myoepithelial carcinoma (EMC) of the parotid gland. Materials and methods Seven patients (four males and three females) aged 40–86 years (mean age, 64 years) with histologically proven EMC of the parotid gland who underwent surgical resection after preoperative MRI were enrolled. MRI images were retrospectively reviewed and contrasted with pathological findings. Results Five patients (71%) had predominantly solid lesions, and two (29%) had predominantly cystic lesions. All seven lesions had well-demarcated margins and capsules without the invasion of adjacent structures. The capsules were incomplete in five lesions (71%) and complete in two (29%). Four lesions (57%) exhibited a multinodular structure with internal septa. Cystic components were observed in three lesions (43%). On T1-weighted images, the solid components were frequently homogeneous (5/7, 71%), and demonstrated isointensity in five lesions (71%) and hypointensity in two (29%) relative to the spinal cord. On T2-weighted images, the solid components were usually heterogeneous (6/7, 86%), and demonstrated hyperintensity in five lesions (71%) and isointensity in two (29%) relative to the spinal cord. The mean apparent diffusion coefficient value of the solid components was 0.967 × 10 −3 mm 2 /s. Conclusion Parotid gland EMCs usually appeared as predominantly solid lesions with well-demarcated margins and capsules. A multinodular structure with internal septa was characteristics of EMCs.