CREB1 and mesenchymal cell neoplasm: In conclusion, MN-NEs represent only a small group among the various NEN mimickers, but have been increasingly noticed in recent years and are particularly found among new entities of mesenchymal tumors that share an epithelioid-mesenchymal morphology, show a variegated immunophenotype, are characterized by gene fusion alterations in the CREB family or mutations of SMARC genes, and can occur as pancreatic primaries.