Lymphatic/vascular invasion & nodal disease
Lymphatic/vascular invasion
- Best assessed around periphery of tumour
- Difficulty distinguishing from shrinkage artefact in section - do not overdiagnose!
- Lymphatics tend to accompany small veins arteries and nerves - if seen improves confidence in diagnosis
- Tumour in vessels tends to be 'stuck' to the sides and may be accompanied by red cells
- An independent prognostic factor so do not diagnose just because the nodes are positive!!
A cuff of lymphatic invasion around a small vein in a vascular bundle
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Further examples of lymphatic/vascular invasion
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The images below are from the same case.
On the left the arrow points to a possible focus of lymphatic invasion; on the right lymphatic invasion is unequivocal.
The diagnosis is made considerably more secure by confirming the presence of a lymphatic "in company" with a vein and small artery
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An example of NOT lymphatic/vascular invasion. This is a rtraction artefact and is very common.
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Nodal metastases
- Identification of nodal metastatic disease is the most important task facing the pathologist examining an operative lymph node specimen in a case of breast cancer
- Microscopic assesment should include the size of the largest metastasis, extranodal extension & invasion of adjacent lymphatics if present
- Node metastases are subclassified into - replacement type, micrometastases and isolated tumour cells (ITCs) according to TNM 6 - see below
- Subtle subcapsular or intrasinusoidal metastases can be difficult to distinguish from sinus histiocytosis - use a cytokeratin stain if in doubt
- Lymph node metastases may be particularly subtle with invasive lobular carcinoma
Subclassification of nodal metastases (TNM6)
| Replacement metastases |
≥ 2mm |
| Micrometastases |
0.2mm-2mm |
| Isolated tumour cells |
< 0.2mm |
