MKI67 and Wilson disease: In contrast, WD-NENs, despite mostly featuring a low/intermediate differentiation grade, may contain regions with an increased proliferation rate that places them, in accordance with the WHO, in the WHO G3 category.15 Specifically, G3 NENs with a WD morphology are commonly Ki67 positive (>20% but usually <55%) and respond poorly to cisplatin-based treatment.