Example of intratumoral heterogeneity in a digestive tract neuroendocrine tumor

Example of intratumoral heterogeneity on the same slide in a single tumor.
(A) A single high-power field (HPF) from one area shows no mitotic figures (H&E, 400x original magnification).
(B) HPF from another area of the same tumor shows four mitotic figures (H&E, 400x original magnification).
(C) Ki-67 staining in the same area as "A" shows a labeling index of <1% (grade 1) (200x original magnification).
(D) Ki-67 staining in the same area as "B" shows a labeling index of 3.4% (grade 2) (200x original magnification).