To date, the clinical value of lymph node size in colon cancer has been investigated only in a few studies. Only in radiological diagnosis is lymph node size routinely recognized, and nodes Z10 mm in diameter are considered pathologic. However, the few studies regarding this topic suggest that lymph node size is not a reliable indicator of metastatic disease. Moreover, we hypothesized that increasing lymph node size is associated with favorable outcome. By performing a morphometric study, we investigated the clinical significance of lymph node size in colon cancer in terms of metastatic disease and prognosis. A cohort of 237 cases with excellent lymph node harvest (mean lymph node count: 33±17) was used. The size distribution in node-positive and -negative cases was almost identical. In all, 151 out of the 305 metastases detected (49.5%) were found in lymph nodes with diameters r5 mm. Only 25% of lymph nodes 410 mm showed metastases. Minute lymph nodes r1 mm were involved only very rarely (2 of 81 cases). In 67% of the cases, the largest positive lymph node was o10 mm. The prognostic relevance of lymph node size was investigated in a subset of 115 stage I/II cases. The occurrence of Z7 lymph nodes that were 45 mm in diameter was significantly associated with better overall survival. Our data show that lymph node size is not a suitable factor for preoperative lymph node staging. Minute lymph nodes have virtually no role in correct histopathological lymph node staging. Finally, large lymph nodes in stage I/II disease might indicate a favorable outcome.

Recently, we introduced ex vivo intra-arterial methylene blue injection into the inferior mesenteric artery as a novel method to improve lymph node (LN) harvest in rectal cancer. We have now adapted this method to the other segments of the colon. A total of 60 cases were enrolled. Primary LN dissection was followed by fat clearance and a secondary dissection. The mean +/- SD primary LN harvest differed highly significantly with 35 +/- 18 and 17 +/- 10 LNs in the methylene blue-stained and unstained groups, respectively. Primary insufficient LN harvest occurred in 8 cases of the unstained group and in only 1 case of the methylene blue-stained group (P = .0226). After secondary dissection, upstaging was seen exclusively in the unstained group. The time/LN ratio differed significantly with 0.9 and 0.6 min/LN in the unstained and methylene blue-stained groups, respectively. Intraarterial methylene blue injection is recommended as a routine technique in the histopathologic study of colon cancer.

Pericolonic tumor deposits (PTDs) are associated with an adverse outcome in colorectal cancer. According to the International Union Against Cancer they are classified as N1 or V1/V2 depending on their shape. This recommendation, however, is not well supported by the literature. To elucidate the origin of PTDs, we performed a histomorphologic study of 69 PTDs, which were found in 7 of 21 colorectal specimens using the whole-mount step-section technique. Depending on the origin, the nodules were classified as venous invasions, lymphatic invasions, nerve sheath infiltrations, free PTDs, and continuous growth in 18 (26%), 3 (4%), 6 (9%), 34 (49%), and 8 (12%) of 69 PTDs, respectively. Polycyclic and oval-round shapes were identified in all categories. Continuous growth was found only within the inner third of the adhering fat, whereas the other morphologic features were found in all regions. The data of this study do not support PTD classification on the basis of their shape.

The results of our study show that tumour budding and the plasmin/plasminogen system are related. PAI-1 was independently predictive for the occurrence of distant metastasis.

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