Figure 4. The neuroendocrine nature of a tumor is confirmed by positive staining to Chromogranin A (E). Tumor grade is based on mitotic count and Ki67 index. Mitotic count is measured on standard H and E sections, with examples of low counts (A, higher power C), and high counts (B, higher power D). Also shown are examples of tumors with low (F) and high (G) Ki67 proliferative index.