In most cases, highly proliferative carcinoids can be readily recognized morphologically as belonging to the carcinoid/NET family due to their bland, uniform cytology, absence of necrosis (or presence of only focal punctate necrosis), and heterogeneous pattern of Ki67 elevation with hot-spots interspersed with low-proliferative areas (Fig. 1). Here, MKI67 is linked to carcinoid tumor.