Figure 1.

Pitfalls introduced in assessing sTILs in breast cancer. (A-B) Marked heterogeneity in sTILs density within the tumor. (B) Lymphocytic infiltrates of varying densities separated by collagenous stroma. (C-I) Challenges associated with delineating the stromal regions including limited stromal areas within tumor (C), necrosis (D), adipose tissue (E), peritumoral retraction clefting (F), histiocyte response (G), cholesterol deposition (H), and lipofuscin deposition (I). A: H&E staining, 4×; B-I: H&E staining, 10×. H&E, hematoxylin–eosin; sTILs, stromal tumor-infiltrating lymphocytes.