LAUSR

Tumor invasion into the endothelial‐lined spaces (lymphatics and medium/ large veins) is a poor prognostic marker in various malignancies. As per the AJCC tumor‐node‐metastasis (TNM) staging system (AJCC Cancer Staging Manual, 8th edition), one has to look for and comment on the extramural venous invasion (VI) to predict distant tumor metastasis. Presence of VI also qualifies a patient to receive systemic adjuvant chemotherapy in TNM stage II and stage III colorectal carcinomas (CRCs).[1] Tumor invasion in the small vessels, comprising lymphatics, capillaries, and postcapillary venules (all considered under ‘L’ classification in current TNM staging system) is also a marker of higher lymph node (LN) metastasis.[2] Tumor deposits (TD) [tumor satellites] are the discrete macroscopic or microscopic tumor cell nodules, in the pericolorectal adipose tissue, discontinuous from the primary tumor without any histological evidence of residual LN, or vascular or neural structures. If a vessel wall can be demonstrated around a TD, the same should be classified as either a venous invasion (V1/2) or lymphatic invasion (L1), respectively. Like the VI, the presence of TDs also does not change the primary tumor ‘T’ category, but changes the LN status (N) to pN1c, in a regional LN‐negative CRC. In stage II CRC presence of pN1c further, upstage it to stage III. Though in previous editions of AJCC size of TDs (in TNM5) and their outer contour (in TNM6) were taken into account to differentiate them from pericolorectal metastatic LNs, neither size nor contour is part of the current definition of TD in AJCC 8th edition.[1,2]