MKI67 and neuroendocrine carcinoma: Neuroendocrine carcinomas (NECs), whether small-cell (SCNECs) or large-cell (LCNECs), exhibit aggressive clinical behavior and poor prognosis, characterized by high-grade nuclear features, high mitotic counts (often >20 per 2 mm2), and a Ki-67 index usually exceeding 55% (15).