Patient 1
An 83-year-old woman presented with painless swelling in her right parotid gland without facial paralysis. Neck contrast-enhanced computed tomography (CT) showed a primary parotid tumor (24 × 19 × 16 mm in size) and no cervical metastases. Fluorine-18 fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) showed abnormally high FDG uptake in the right parotid gland. Superior parotidectomy was performed without capsule rupture and with free margins; the pathologic stage was pT2N0M0. Pathologically, the tumor was multinodular with biphasic tubules and solid nests (Fig. 1a). Immunostaining showed positivity for cytokeratin (CK) AE1/AE3 in ductal epithelial cells and for SMA and p63 in myoepithelial-like cells (Fig. 1b, c). The Ki-67 labeling index (LI) was approximately 12%. Sanger sequencing revealed the HRAS Q61R mutation. Thus, the patient was diagnosed with EMC. One-year follow-up revealed no local recurrence or metastasis.