CRTC1 and mucoepidermoid carcinoma: Low-grade tumors generally do not have genomic imbalances and are positive for CRTC1-MAML2 gene fusion, whereas high-grade tumors mainly show numerous genomic imbalances and negative gene fusion.[12] In our patient, the final pathological diagnosis was high-grade MEC, and the CRTC1-MAML2 fusion transcript could not be identified using FISH.