The latest update in the 2022 WHO classification of neuroendocrine tumours consolidates the utility of this dichotomous morphological subdivision made on criteria based on the tumoral differentiation: NETs are generally (but not always) graded as G1, G2 or G3, usually presenting a low ki67 index, while NECs are by definition high grade (ki67 > 55%), presenting cellular polymorphism [6]. The gene discussed is MKI67; the disease is neuroendocrine neoplasm.