Methylene Blue–Assisted Lymph Node Dissection in Colon Specimens

Abstract

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.

Methylene blue-assisted lymph node dissection technique is not associated with an increased detection of lymph node metastases in colorectal cancer

“…Moreover, the usefulness of this technique has been approved by several other groups. [23][24][25][26][27][28][29][30] This study showed again that dramatic improvements are seen with the use of advanced lymph node dissection techniques (Figures 1 and 2). This was especially true in neoadjuvantly treated rectal cancer cases-a situation strongly associated with low lymph node counts.…”

“…The technique has been described before. 23,24 In brief, an ex vivo intra-arterial injection of 15-20 ml of methylene blue solution is performed in the fresh or shortly formalin-fixed (r 4 h) specimen. Lymph nodes were then dissected manually after fixing overnight.…”

“…In another 55 cases, the methylene blue-assisted lymph node dissection technique and fat clearance were combined. 23,24 Sequential Lymph Node Dissection Sequential lymph node dissection was performed in a subset of 94 cases. In these cases, the mesenteric fat of the specimens was divided into three parts: the tumor region, the proximal and the distal parts.…”

“…In 2007, we introduced the methylene blue-assisted lymph node dissection method as a cheap and simple alternative method to improve lymph node harvest in gastrointestinal cancers. 23,24 The aim of this study was to investigate the effect of an advanced lymph node dissection technique dependent on different clinicopathological factors (age, location, T-stage, therapy, and so on) in a large study group compared with a historical control group of equal size. Moreover, we addressed the question of whether an improved yield is associated with an increase in the node positivity rate and therefore influences the stage-related outcome.…”

The clinical significance of lymph node size in colon cancer

“…Recently, we introduced methylene blueassisted lymph node dissection as a cheap and highly effective method to guarantee optimal lymph node staging in gastrointestinal cancers, with lymph node numbers by far exceeding the general recommendations. [13][14][15][16] This improvement is mainly the result of better visibility of small lymph nodes. Therefore, the question arises as to whether the detection of such small lymph nodes is clinically significant.…”