Ex vivo sentinel node mapping in carcinoma of the colon and rectum

Ann Surg. 2001 Apr;233(4):515-21. doi: 10.1097/00000658-200104000-00006.


Objective: Increasing evidence supports that the sentinel node (SN) is at greatest risk for harboring metastatic disease. This study describes a novel technique to identify the SN in colorectal carcinoma.

Methods: Within 30 minutes of resection, colorectal specimens were injected submucosally with isosulfan blue in four quadrants. Blue lymphatic channels were identified in the mesentery and followed to the blue-stained SN(s), which were then harvested. The specimen was fixed in formalin and subsequently analyzed in the usual fashion. Blue-stained nodes that were negative by hematoxylin and eosin staining were further analyzed by immunohistochemical staining.

Results: During a 6-month period, 26 patients with adenocarcinoma of the colon and rectum undergoing routine resection were studied. There were 18 men and 8 women ranging in age from 29 to 86 years (median 66). Blue-stained SNs were identified in 24 of 26 specimens. The mean number of SNs identified per patient was 2.8 +/- 1.6. Seventy-three SNs were identified from a total of 479 lymph nodes harvested. The mean number of nodes identified per patient was 18.4 +/-7. A total of 67 lymph nodes in 12 patients were identified by hematoxylin and eosin staining to have evidence of metastatic disease. Fourteen (20%) of these nodes in six patients were stained blue. However, with immunohistochemical staining, only one blue node did not have evidence of metastatic tumor in a lymphatic basin with tumor present. Four patients (29%) whose lymphatic basins were negative by hematoxylin and eosin staining were upstaged by immunohistochemical staining of the SN.

Conclusions: Ex vivo mapping of the colon and rectum is technically feasible and may provide a useful approach to the ultrastaging of colorectal carcinoma.

MeSH terms

  • Adenocarcinoma / pathology*
  • Adenocarcinoma / secondary
  • Aged
  • Colorectal Neoplasms / pathology*
  • Coloring Agents
  • Female
  • Humans
  • Lymph Nodes / pathology
  • Lymphatic Metastasis
  • Male
  • Rosaniline Dyes
  • Sentinel Lymph Node Biopsy*
  • Sigmoid Neoplasms / pathology*
  • Specimen Handling


  • Coloring Agents
  • Rosaniline Dyes
  • iso-sulfan blue