Related Experiment Video
Updated: May 26, 2026
The Application of 1% Methylene Blue Dye As a Single Technique in Breast Cancer Sentinel Node Biopsy
Published on: June 1, 2019
Absence of ectopic epithelial inclusions in 3,904 axillary lymph nodes examined in sentinel technique
Sonja Iken1, Marcus Schmidt, Claudia Braun
1Department of Pathology, Johannes Gutenberg University, Medical School, Langenbeckstrasse 1, 55131 Mainz, Germany sonja.iken@kgu.de
Insights
Ectopic epithelial inclusions in axillary lymph nodes are rare. This autopsy study found no such inclusions, challenging previous assumptions about false-positive results in sentinel lymph node biopsies.
Area of Science:
- Pathology
- Surgical Oncology
- Molecular Diagnostics
Background:
- Intraoperative sentinel lymph node examination aids cancer staging.
- PCR-based cytokeratin detection may yield false positives due to benign epithelial inclusions.
- The incidence of these inclusions is debated, with prior estimates around 5%.
Purpose of the Study:
- To determine the actual incidence of ectopic epithelial inclusions in axillary lymph nodes.
- To assess the frequency of potential false-positive results in PCR-based sentinel lymph node analysis.
Main Methods:
- Autopsy study of 3,904 lymph nodes from 160 axillary dissections in 80 patients.
- Examination of 100 μm step sections using hematoxylin-eosin and pan-cytokeratin immunostaining.
- Systematic evaluation of lymph nodes from levels 1, 2, and 3.
Main Results:
- No epithelial inclusions were identified in any of the examined axillary lymph nodes.
- The meticulous examination involved over 30,000 slides.
- This finding suggests a significantly lower incidence than previously reported.
Conclusions:
- Ectopic epithelial inclusions in axillary lymph nodes appear to be extremely rare.
- The risk of false-positive sentinel lymph node diagnoses due to these inclusions may be negligible.
- Further investigation into diagnostic methodologies for sentinel lymph nodes is warranted.
Abstract:
Intraoperative examination of sentinel axillary lymph nodes can be done by imprint cytology, frozen section, or, most recently, by PCR-based amplification of a cytokeratin signal. Using this technique, benign epithelial inclusions, representing mammary tissue displaced along the milk line, will likely generate a positive PCR signal and lead to a false-positive diagnosis of metastatic disease. To better appreciate the incidence of ectopic epithelial inclusions in axillary lymph nodes, we have performed an autopsy study, examining on 100 μm step sections 3,904 lymph nodes obtained from 160 axillary dissections in 80 patients. The median number of lymph nodes per axilla was 23 (15, 6, and 1 in levels 1, 2, and 3, respectively). A total of 30,450 hematoxylin-eosin stained slides were examined, as well as 8,825 slides immunostained with pan-cytokeratin antibodies. Despite this meticulous work-up, not a single epithelial inclusion was found in this study, suggesting that the incidence of such inclusions is much lower than the assumed 5% reported in the literature.
