[Pathological process for sentinel lymph node]

Area of Science:

• Oncology
• Pathology
• Surgical Oncology

Background:

• The sentinel node is the primary site of lymphatic drainage from a tumor.
• Sentinel node biopsy (SNB) has revolutionized lymph node staging in various cancers.
• Accurate pathological assessment of the sentinel node is crucial for treatment planning.

Purpose of the Study:

• To review and compare histological protocols for sentinel node examination across different organs.
• To evaluate the efficacy of various pathological techniques for detecting metastases in sentinel nodes.
• To provide guidance on optimal sentinel node processing for accurate cancer staging.

Main Methods:

• Literature review of histological protocols for sentinel node analysis.
• Comparison of intraoperative techniques (frozen section, touch imprint cytology).
• Analysis of histological ultrastaging methods, including sectioning intervals and immunohistochemistry.

Main Results:

• Intraoperative frozen section is more sensitive than touch imprint cytology for sentinel node evaluation, except in breast cancer and melanoma.
• Complete embedding and serial sectioning (2mm intervals) of the sentinel node are recommended.
• Histological ultrastaging with three serial sections (200-250 microns) can detect most micrometastases.
• Systematic immunohistochemistry is not routinely necessary for breast cancer SNB but is valuable for other organs.

Conclusions:

• Standardized histological protocols for sentinel node examination are essential for accurate cancer staging.
• Histological ultrastaging significantly improves the detection of occult metastases.
• Tailored approaches to sentinel node pathology, including the use of immunohistochemistry, are beneficial depending on the primary tumor site.