SUPREMO Pathology Pictures

This page reiterates the Pathology Pictures section of the SUPREMO protocol for ease of reference and gives illustrative guidance on grading, assessing lymphatic invasion and lymph nodes for pathologists. We acknowledge that these assessments are prone to some subjective interpretation and to that end we would welcome feedback via the SUPREMO web site.

In the majority of the photographs additional description can be obtained by passing the mouse arrow over the image. In a small number of illustrations the image will change on passing the mouse over it. These additional features will not always function in some web browsers.

The photomicrographs will be viewed optimally at a screen resolution of 1024 x 768 and viewers should bear this in mind when setting up their systems.

The SUPREMO Pathology Pictures Protocol

UICC staging (6th edition) should be used.

7.1.1 The size of the primary tumour should be measured.

7.1.2 All primary tumours should be graded according to the Nottingham modification of the Bloom & Richardson grading system.

7.1.3 The adequacy of the excision margin should be measured. An adequate margin is any margin that is deep, anterior or radial. The margins are to be clear of either invasive or non-invasive disease, that is invasive carcinoma or ductal carcinoma in situ (DCIS). It does not include the presence or absence of lymphatic/vascular invasion.

7.1.4 A minimum of 10 axillary nodes should be examined in an axillary clearance.

7.1.5 All submitted axillary nodes in a axillary node sample should be examined.

7.1.6 A copy of the Pathology Pictures report on the primary tumour and axillary node(s) should be sent to the trial administrator.

7.1.7 The original reported grade and lymphovascular status will be accepted for the purpose of the trial.

7.1.8 A password protected website for the trial will be provided giving examples of grading and lymphovascular invasion to facilitate standardisation of reporting between pathologists.

7.1.9 A panel of three pathologists will undertake the review of all cases entered by examining a representative H&E section taken from the block submitted to the trial central laboratory. Each pathologist will review one third of the cases, randomly allocated, and assess grade and lymphatic/vascular invasion. The pathologists will be blinded to the original Pathology Pictures report. Those cases where the review grade and lymphatic/vascular invasion status is in agreement with those originally reported will be reviewed no further. In those cases where there is disagreement between the reviewing pathologist and the original report there will be a formal review by all three reviewing pathologists to achieve consensus. Criteria for review will conform to current grading guidelines (Elston CW and Ellis IO. Pathological prognostic factors in breast cancer: experience from a large series with long term follow up. HistoPathology Pictures 1991; 19:403-10).

7.2. Multifocal invasive cancer: If the tumour area comprises multiple small adjacent foci of invasive carcinoma then the overall maximum dimension should be taken and must be greater than 2cm if N0 (see Diagram F below):

• Histological grade provides important prognostic and management information
• The internationally accepted system is that defined by Elston and Ellis1
• Assess by evaluating acinar formation, nuclear size/pleomorphism and mitotic activity
• Nuclear evaluation is the most subjective and can lead to inconsistency
• Although originally designed for grading NST tumours it is recommended that it is applied to all cancers
• An attempt should be made to grade the pre-operative core biopsy as there is acceptable concordance with excision grade

Scoring system

• Each element evaluated is given a score of 1 - 3
• Acinar/tubule formation is assessed over the whole tumour and is a low/medium power assessment
• Nuclear evaluation is of the worst area
• Mitotic count is also in the most mitotic area

When assessing mitotic count it is essential to calibrate your microscope so that you know the diameter of your (x40) hpf. Readers are referred to the calibration table in the UK breast screening guidelines².

A minimum a 10 hpfs should be counted at the periphery of the lesion and an attempt made to seek out mitoses. The illustrations below show examples of what are and more importantly what are not mitoses. It is especially important not to count apoptitic bodies and other dark nuclear blobs.

The following score groupings are used to define the Grade of a cancer. When reporting the Grade it is good practice to give the individual score components as well as the calculated grade. This allows for possible audits in the future and also allows for immediate comment on comparisons with core grade (if its score components have also been recorded).

It is worthwhile when trying to assess tumour grade identifying those elements about which you have no doubt and then looking at the remaining scoring element(s) which may or may not be critical depending whether the two most likely scoring options push the grade one higher or one lower. In the following example the final element may or may not be non-critical depending on whether the scoring decision is between 1 & 2 or between 2 & 3. Obviously we do not want to encourage sloppy practice, on the contrary, simply a more robust approach to the practicalities of grading:

• Tubule score unequivocally 2
• Mitotic score unequivocally 2
• Nuclear score non-critical - if 2 v 3 but critical if 1 v 2

• Tubule score unequivocally 3
• Nuclear score unequivocally 3
• Mitotic score (1 v 2) critical for deciding between grade 2 and grade 3

• Tubule score unequivocally 2
• Mitotic score unequivocally 2
• Nuclear score (1 v 2) critical for deciding between grade 1 and grade 2

Examples of Tubule Formation

When assessing tubule formation, having initially assessed the tumour at scanning power examine some representative fields more closely picking out ten epithelial units at a time and estimating how many are solid and how many have a glandular space. Very quickly you will have a very good idea whether it is < 10% or > 75%.

Tubule score = 1 (>75% tubules)

Tubule score = 2 (10 - 75% tubules)

Tubule score = 3 (< 10% tubules)

Examples of the three nuclear grades

NOTE - All the nuclear grading photographs have been taken at identical magnification for ease of comparison

Four examples of Nuclear score = 1

Two examples of a mixture of Score 1 and Score 2 nuclei (see arrows) - this is predominantly nuclear score = 1 however the higher nuclear grade always applies when there is a mixed population

Two examples of Score 2 nuclei - lower end of the range on the left, the higher end on the right

Four examples of Score 3 nuclei from the lower end of the range (top left) to the higher end (bottom right)

Examples of mitoses (Y) and not mitoses (N)

The following examples are from a selection of nuclear grade 3 carcinomas which show brisk mitotic activity. Various nuclear changes have been marked as to whether the author believes them to be (Y) or not to be (N) mitoses. It is inevitable that different pathologists will argue over some of these!

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!!

Examples of lymphatic/vascular invasion

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 in the right hand image. Pass the mouse over these images to change the view.

An example of probable retraction artefact and NOT lymphatic/vascular invasion

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

Subclassification of nodal metastases (TNM6)

Replacement metastases	> 2mm
Micrometastases	0.2mm-2mm
Isolated tumour cells	< 0.2mm

Replacement Metastases

Two examples of replacement metastases in axillary nodes. Note extra-capsular spread into adjacent fat in the images on the right

Micrometastases

Subcapsular micrometastasis - this deposit is < 2mm on the H&E but the immuno stain for pan CK was on a section taken after cutting into the block further and measures just over 0.2mm qualifying as a micrometastasis

Isolated Tumour Cells and Micrometastases

Two subtle subcapsular deposits (arrows) of metastatic carcinoma in an axillary node sample -
the sentinel node was negative in this case.
The deposit in the upper left quadrant measures <0.2mm and on its own would be recorded as "isolated tumour cells" (N0)
The deposit in the lower right hand quadrant measures 0.27mm and therefore qualifies as a micrometastasis (N1)

The enlarged photomicrograph below shows more detail of the metastatic foci when you move the mouse over those areas

References

© Dr Jeremy Thomas 2005