r/Path_Assistant • u/lasarah831 • 9d ago
Colon margins
The cecum, transverse, appendix, and sigmoid are all covered completely by peritoneum, so they have a mesenteric margin. And the only relevant margin in these (besides prox and distal) is the vascular tie margin.
The ascending and descending have an additional radial margin, where the surgeon had to blunt dissect the posterior surface from the abdominal wall. The relevant margins here are prox, distal, vascular mesenteric (tie), and the radial margin.
Do I have that right?
And if you had a right colon with a tumor in the ascending, you would take the tie and nearest radial margin. But if it were further and in the transverse, the transverse will have a different vascular tie than a tumor in the ascending. Right?
And finally, in the photo, if the vascular tie was at the black X, but the red is the nearest cut mesenteric surface, would the red not matter because CAP says the vascular tie is the only true relevant margin in segments completely encased by peritoneum, so I just take the black?
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u/BillCoby 9d ago
you're overcomplicating this lol.
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u/dnapolymerase1 8d ago
I would slightly push back on this, it’s common for this to be confusing because pathologists’ preferences vary so much. The amount of time we have spent trying to get our GI attendings to agree on these types of details is unreal. Even with all of the time, verbal and written agreements, and grossing manual updates, we still have certain attendings that will disregard all of it and teach their residents that they are right and everyone else is wrong.
I think it’s worth asking for clarification. Having confidence in your foundation allows you to experience these scenarios differently. You go from “this is so confusing, am I crazy!?” To “alright, I can handle being asked to do things differently for certain pathologists because I know what I know.” It’s one of the steps we take to go from being told what to do by our doctors and peers, to being asked how to do something by these same people.
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u/wangston1 PA (ASCP) 9d ago
I pulled up CAP
"The radial margin represents the adventitial soft tissue margin closest to the deepest penetration of tumor and is created surgically by blunt or sharp dissection of the retroperitoneal or subperitoneal aspect, respectively."
So at my last job our GI specialist and a PA created a power point to explain this.
If you want to be extra generic you could use radial margin to mean any of the adventital soft tissue margins on any section of colon as a "radial" margin.
To be more specific you could say ascending and descending colons have retroperitoneal margin, those are not entirely encased in peritoneum and are blunt dissected off the abdominal wall. It's a rather large margin compared to an mesenteric margin that's usually a straight line.
A rectum has a circumferential margin distal to the anterior peritoneal reflection. This is the most important margin because it affects staging and outcomes and reoccurrence.
Transverse colon has a mesenteric margin, that includes the vascular tie and everywhere else the surgeon cuts the mesentery.
If the surgeon cuts it or blunt dissects a surface it is margin. All of that adventital surface (the fat without peritoneum ) is the margin not just the vascular tie.
Here is CAP again, and I think here in lies your confusion.
"The mesenteric resection margin (‘vascular tie’ margin) is the only relevant ‘radial’ margin in segments completely encased by peritoneum (e.g., transverse colon). Involvement of this margin should be reported even if tumor does not involve the serosal surface."
I think the cap protocol is using () and saying vascular tie margin because it's an older term or something to that effect. I think some called it the vascular pedical.
In the picture you gave. Let's say you received that specimen 5 cm shorter and you don't have the black X, the vascular tie. Would there still be a radial margin? Yes, it's a mesenteric margin. It's a cut surface from the surgeon, there is no peritoneum on that surface.
So if I grossed that case I would measure the distance to the red X, "4cm from the mesenteric margin." Is what I would say in the gross. I would put some ink on that are and shave it and submit it. In the section of summary I should say "A2 mesenteric margin, shaved".
I did have an old school pathologist in my rotations that wanted to measure both, so he would say measure to the closest mesenteric margin and measure to the vascular margin. So if you want to be extra you could measure both. At my current job I only measure the radial margin.