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The recent article by Bleicher et al1 described what the authors believed to be the first study evaluating the association between sentinel lymph node (SLN) dye gradients and the location of metastases within the SLNs. Although the authors were not aware of any similar reports, 2 earlier studies documented very similar findings.2, 3

In a study by Cserni,2 40 SLNs from 36 patients were examined. The lymph nodes were removed together with a blue lymphatic channel, and the junction between the lymphatic vessel and the blue lymph node was marked with ink by the pathologist at the grossing bench. Nineteen SLNs had metastases in both the inked half and the opposite half. Eleven had metastases only in the inked half, and 2 had metastases only in the opposite half. Cserni concluded that SLN metastases are more likely to be located in the vicinity of the inflow junction of the lymphatic channel draining the tumor.

We tested the hypothesis at the University of Texas M. D. Anderson Cancer Center by prospectively evaluating 305 SLNs from 213 patients with breast cancer.3 Intraoperatively, the surgeon placed a suture either at the point of entry of the blue dye or at the area with the highest radioactive counts, and the sutured area was inked by the pathologist at the grossing bench. Metastases were identified in 55 of the 305 lymph nodes examined. Thirty-four contained metastases in both the inked half and the opposite half. Eighteen had metastases only in the inked half, and 3 had metastases only in the opposite half. Although Bleicher et al1 were uncertain whether their findings would be applicable to a radioactivity gradient, we found similar results when SLNs tagged at the point of blue dye entry and SLNs tagged at the area with the highest radioactive counts were analyzed separately.

It is encouraging that investigators unaware of our previous findings found such similar results in their prospective trial. Their data, together with the results of the 2 earlier studies, provide compelling evidence that metastases are most likely to be identified in the bluest or hottest half of the SLN. This information could have potential utility in directing a more focused examination of the portion of the SLN most likely to harbor metastatic disease.

References

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  • 1
    Bleicher RJ, O'Sullivan MJ, Ciocca V, et al. A prospective feasibility trial to determine the significance of the sentinel node gradient in breast cancer: a predictor of nodal metastasis location. Cancer. 2008; 113: 3100-3107.
  • 2
    Cserni G. Mapping metastases in sentinel lymph nodes of breast cancer. Am J Clin Pathol. 2000; 113: 351-354.
  • 3
    Diaz LK, Hunt KK, Ames F, et al. Histologic localization of sentinel lymph node metastases in breast cancer. Am J Surg Pathol. 2003; 27: 385-389.

Leslie K. Diaz MD*, Michael Z. Gilcrease MD, PhD†, * Abbott Northwestern Hospital Laboratory, Minneapolis, Minnesota, † Breast Section, Department of Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.