According to their pathological features, pNETs have been categorized as follows: grade 1, which has a well-differentiated morphology and Ki-67 <3%; grade 2, which also has a well-differentiated morphology and Ki-67 3–20%; and grade 3, neuroendocrine carcinomas with Ki-67 >20% and poorly differentiated morphology. The gene discussed is MKI67; the disease is neuroendocrine carcinoma.