Help me learn to find pericolonic lymph nodes...

[MirkoCrocop]

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I've heard the upper levels' methods and I'm not really getting the hang of it. I find myself just mashing through the fat trying to find what might look or feel like a lymph node, although I haven't really heard any good ways of distinguishing LNs from all the other "firm" feeling things in the fat.

So, please enlighten me on what LNs really look like and your methods.

Thanks in advance.

 

[green mantis]

The procedure is different if you're allowed to fix the fat overnight. I have personally used the following fixatives:

1) Bouin's
2) Dissect-aid
3) Karnoy's

I'm sure there are others, but these were the ones available to me. Karnoy's was eventually phased out by the program because it's expensive, & it was replaced by Dissect-aid.

You basically strip the fat from the colon. It's better if you keep it in larger chunks. The following day, you breadloaf each of those chunks into thin slices & look at the cross-section. All of the above work by staining the fat. Lymph nodes remain white. I've had pretty good luck w/ this technique.

If you don't find the required number, then you can mash the thin slices you've made. Gloves take away too much of your tactile sensation, so I prefer to look rather than feel.

Otherwise, there should be no shame is submitted a piece of fat you thought was a lymph node & have it turn out to be a vessel.


----- Antony

 

[levels x3]

I couldn't help but laugh when I read this post. I'm laughing with you of course, because finding lymph nodes is the bane of most junior residents' existence. Actually it's the bane of most pathologists' existence. Grossing a tumor colon would take 10 minutes without the lymph node search.

There are no fool-proof methods or tricks. Distinguishing lymph node from vessel from firm fatty corpuscle just takes time and practice. I'm a masher by the way (more on that later). Large lymph nodes are obviously not a problem, it's the small ones that you need to get your total number up to the needed 12 (at our institution) that can be tricky. Let's not get into why 12 is or is not an appropriate target...

I'm a chief this year and in training a particular 1st year to find nodes a few weeks ago, I remarked that they feel like little pebbles or grains of sand within the fat. I generally mash the fat into paper towels, but I also feel between 2 fingers. Every time I found a small one, I'd pass it over to her to feel. Well she'd promptly squash each node under her finger with Incredible Hulk like force. Light touch people...light touch......Yes you have to mash the fat, but try to develop a light touch.

So here is my method, and it generally works well. First take all of your sections, measurements, etc. from the colon and tumor itself. At this point you don't really care what you do to the rest of the specimen within reason. Cut all of the mesenteric fat off of the colon, paying particular attention to the fat beneath the tumor. It makes no difference to me whether or not the colon/fat are fresh or fixed, though some people think it's easier fresh. Then systematically mash away, putting presumptive nodes on a separate, clean, wet paper towel. Eventually you will start to feel the difference between a vessel and a node, but at first, submit vessels...who cares, if it saves you a trip back to the bucket. I don't have any tricks other than using as light a touch as possible.

Hope that's helpful and I'll be curious what others have to say. Just relax and know it's a sucky task for everyone.

 

[djmd]

Lymph node tricks/tips (in no particular order)

-fat smashes lymph nodes don't (under normal pressure), use a paper towel to help with the grease, I use a side press/smear move, straight down is too easy to crush the node.

-Lymphatics generally parallel vessels

-when make initial cuts, cut a parallel to vessels and use a light touch, because the lymph node is usually loose enough to move out of the way for the blade, which will allow you to spot it. (better than bisecting a lymph node)

- submit only one half (the larger) of accidentally bisected LN (unless large) (put the other half in a separate paper towel to avoid submitting)

- do submit things you are sure are lymph nodes (learn)

- do submit equal sized items together

- don't submit more than 6-8 objects per cassette (they may fit but unless you histology tech are top flight they will never ger 10+ objects in a single section) (and do get deepers on blocks where you are missing 5 of you 8 objects)

- never stop because you have 15, 20, 30 whatever.. sweep the entire fat. Of cases I have with postive nodes nearly 50% have 1 small LN + out of 30. Stopping with the first definate 15 is a mistake...

 

[CameronFrye]

Lymph node tricks/tips (in no particular order)

-fat smashes lymph nodes don't (under normal pressure), use a paper towel to help with the grease, I use a side press/smear move, straight down is too easy to crush the node.

-Lymphatics generally parallel vessels

-when make initial cuts, cut a parallel to vessels and use a light touch, because the lymph node is usually loose enough to move out of the way for the blade, which will allow you to spot it. (better than bisecting a lymph node)

- submit only one half (the larger) of accidentally bisected LN (unless large) (put the other half in a separate paper towel to avoid submitting)

- do submit things you are sure are lymph nodes (learn)

- do submit equal sized items together

- don't submit more than 6-8 objects per cassette (they may fit but unless you histology tech are top flight they will never ger 10+ objects in a single section) (and do get deepers on blocks where you are missing 5 of you 8 objects)

- never stop because you have 15, 20, 30 whatever.. sweep the entire fat. Of cases I have with postive nodes nearly 50% have 1 small LN + out of 30. Stopping with the first definate 15 is a mistake...

I agree with all of this, although I typically use the "fix in clearing agent overnight and then thinly slice the next day" method. This typically isn't a problem since it seems like most of our colons come in on Friday anyway. I almost always find at least 25 or 30 nodes. I once had a case that scared me into being as careful as possible: I found 74 lymph nodes and only two of them were positive.

For all other lymph node searches (esophagus, neck dissections, lymphadenectomies, etc.) I use a combination of touch, sight, and squashing. It's hard to teach though and it really is a learned skill that you will eventually pick up. I actually save a lot of my LN searches for the end of the day, when the support staff has gone home and I can just crank the music and take a little mindless breather (of course, if the tissue processors are getting ready to start, it ratchets up the pressure again).

 

[yaah]

I don't have any tricks or suggestions other than sheer patience. Colons either have >25 nodes or <5, it seems. Don't neglect the fat close to the colon wall. Do neglect the epiploic fat - lots of junior residents get hung up on looking through that - there are no lymph nodes there. I have never found the clearing agents useful. Bouin's makes everything firmer, plus it smells bad. The other stuff doesn't really work either. Or at least if it does work, it is no better than formalin which firms up nodes quite well on its own. But unfortunately, as I said, there is no substitute for just taking the time to do it.

 

[MirkoCrocop]

thanks for the great tips! ill definitely be putting these to use

 

[LADoc00]

Dissect aid pretty much here. But I farm this skill out, havent dissected nodes out in years now.

 

[stickyshift]

Lymph node tricks/tips (in no particular order)

-fat smashes lymph nodes don't (under normal pressure),

Except for the ones with metastatic carcinoma--those smash really easily (onto your glove, which results in tumor floaters on everything else you touch).

 

[djmd]

Except for the ones with metastatic carcinoma--those smash really easily (onto your glove, which results in tumor floaters on everything else you touch).

I have never had that happen... I guess it could, but I have never had that happen in the dozens of colon cancer with + nodes I have grossed.

Now getting cancer all over lymph nodes from a primary tumor would be a real concern. But I generally change gloves between grossing a messy primary and grossing nodes.

 

[raspberry009]

-fat smashes lymph nodes don't (under normal pressure),

I end up mashing lymph nodes all the time on accident. I have to go by that tan color. But they all look different on each person. Once I find one, I sometimes end up going back through to make sure I didn't miss any.

 

[Brian Pavlovitz]

I'm a masher, too. I've found that, for some reason, my thumb does a pretty good job at identifying those nodes that I can't see.

By the way, it's my third year, and it's only recently that I've been able to get at least the magic 12 nodes per colon (provided they haven't been irradiated already). Just takes patience and practice.

 

[KluverB]

Dissect aid all the way! Easily averaging 20-40 LNs per avg segment of bowel resected. Irradiated LARs a little more difficult since most LNs are <1-2 mm, so less to recover there. I'll mash on occasion, but tend to regret that decision every time.

 

[deschutes]

Keep a very low threshold for submitting "possible lymph node".
If I accidentally bisect a node, I just ink the slices and make sure to say in my summary of sections "Cassette #20: two lymph nodes, one bisected (inked orange)".

The separate wet paper towel for keeping your "possible LN" aside is a good idea. Also keep your thin-sliced+mashed stringy fat in a "done" pile so stuff doesn't get mixed up and you don't throw your possible LNs away by accident and have to go dumpster-diving.

My personal preference is no Bouins/Carnoy's/Penfix etc. I hate going back to the bucket for lymph nodes (have had to do this only twice in 3 years, and the second time there were no additional found).

As to how they look: They're usually pink-tan 😀 Sometimes with a little bloody center. Sometimes all red from congestion. Don't leave mesenteric fat stuck to the colon. That's prime lymph node territory.

Mets tend to look whiter and feel/cut firmer. Nodes with mets tend to be larger, but reactive nodes can reach humongous sizes.

~

My thing right now is reporting lymph node counts, when say something labelled "Left peri-aortic lymph nodes" arrives in fragments. I'm convinced it's all voodoo.

 

[listeriaismfb]

I was a masher, too. One of our PAs (also a masher) would get into a "zone" while performing this task - routinely recovering >50 nodes per hemicolectomy! The metastatic nodes were always the really teensie ones.

I really detested the rectal CA/APR cases, the radiation prior to surgery always nuked the nodes right to hell. Once, I had a case that I went back to twice (the node-seeking PA went back the third time), still only like 5 nodes in toto. Awful.

 

[Napoleon1801]

Oh yeah, something I learned a couple days ago that was invaluable to add to the discussion. Because we had an irradiated sigmoid colon we only found 4 nodes after going through it 3 times each, so then we just started submitting blood vessels (4 cassettes worth) and fat to get the magical 12. There were a bunch of microscopic nodes <2mm and we made it to 12 all from the fat!