MIB1 and large cell neuroendocrine carcinoma: Aggressive features on histopathology include high mitotic activity (>2/10 high power fields), Ki-67 index, and presence of necrosis and hemorrhage.4, 8The patient in our case had a primary renal LCNEC (high grade) with size greater than 4 cm, high-risk features of necrosis, high MIB1 index, and high mitotic index.