. 2018 Jul 20;473(4):405–412. doi: 10.1007/s00428-018-2408-z

Table 2.

Summary of the difficulties occurring during scoring the tumor-stroma ratio in colon adenocarcinomas with recommendations on how to act on them

Difficulty	Recommendation
Mucinous tumor	Mucus should be ignored for scoring^a
(Abundant) inflammatory cell infiltration	Infiltration with inflammatory cells is not an exclusion criteria and can be included in the scoring.
Necrotic tissue	Necrotic tissue should be left out of the microscopic field. If this is not possible, the necrotic parts will have to be ignored for scoring^a
Smooth muscle tissue	Smooth muscle tissue should not be considered for scoring. In case it is not possible to select a suitable field without smooth muscle tissue (e.g., in stage II tumors), this tissue compartment should be ignored for scoring.^a A desmin stain may be of assistance.
Glandular lumen	Areas of glandular lumens are ignored for scoring^a
Blood vessels	Small vessels are included as part of the stroma. Large vessels with a muscular wall (> 3 layers of smooth muscle cells) should be avoided or else ignored for scoring^a
Tumor budding cells	Budding adenocarcinoma cells should be separated from the surrounding stroma, and may be highlighted by a cytokeratin stain (AE1/AE3 is recommended) in problematic cases.
Hyalinization	Part of the stroma and therefore included for scoring

^aTo ignore areas for scoring: the microscopic field minus the tissue that has to be visually ignored is set at 100%. The stroma percentage has to be determined from only the solid (= neoplastic + vital stromal compartment) tissue parts