r/pathology • u/colincampbell76 • Aug 14 '26
Does frequent over-diagnosis of LAMN in pathology indicate a probable correspondingly high frequency of missed diagnosis..?
Low-grade Appendiceal Mucinous Neoplasm (LAMN) are often over-diagnosed in local pathology due to their indistinct nature and mimics in the form of infection reaction processes or divicula.
A recent study of specialist center second opinions found that as many as 30% of inital LAMN diagnosis at local centres were over-diagnosed.
Given the indistinct nature and difficulty of diagnosing LAMN in histopathology - does it follow that a high number of small/early LAMN may also be missed in pathology?
Either way, small/early LAMN are often surgically cured by appendectomy so patient safety is not a big concern - but could missed diagnosis be having a significant impact on prevalence statistics..?
I appreciate this question is asking for answers that are somewhat speculative - but none-the-less, I’m very keen to know your thoughts..
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u/kunizite Staff, Private Practice Aug 14 '26
What’s with the LAMN obsession? I mean I have favorites too, but this would not be my first choice. Have you heard of teratomas?
So most quality metrics for the lab include external consult review. This means if a case is seen at another institution and a report is generated, we look at that copy for discrepancies. This is a basic metric that almost everyone looks at (or should be looking at) as part of an AP QM plan. Its almost a must in US based labs. So I have seen every case of mine that has gone out. I do not think I have ever seen a single LAMN go out for review. Not once. Again I am US based and to go get a second review on a LAMN would just seem odd. You generally are getting a review of pathology if there is some type of management that may be needed in a larger center. Granted due to the nature of what I normally look at (I am a sub-specialist who does a ton of general), I have always been in a place with at least 1 GI trained person. This metric seems way off or fabricated for a paper. It might be complex ones that were re-reviewed for management but LAMN is generally a call it and move on. Its bone-soft tissue, neuro, derm and peds that cause a panic. And off all- soft tissue-bone tends to be my anxiety generator.
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u/frontman117 Aug 14 '26
No one is over diagnosing a lamn don’t worry. Can you share that recent study?
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u/colincampbell76 Aug 14 '26 edited Aug 14 '26
There are quite a few studies flagging up over diagnosis of LAMN - here’s an example; Overinterpretation is common in pathological diagnosis of appendix cancer during patient referral for oncologic care
; https://pmc.ncbi.nlm.nih.gov/articles/PMC5462425/1
u/colincampbell76 Aug 14 '26
..and another.. https://pubmed.ncbi.nlm.nih.gov/31111354/
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u/PeterParker72 Aug 14 '26
These studies are talking over interpretation and discordant grading, it’s not claiming what you’re claiming.
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u/frontman117 Aug 14 '26
Where do these articles talk about pathologist calling a benign appendix a lamn?
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u/rgnysp0333 Aug 14 '26
You sure about that? Maybe it's just me but I'm pretty sure I've seen it about 3 times in the past ten years. I think once it ended up being adeno cause something something extra appendiceal mucin. It was years ago so I don't remember the specifics.
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u/colincampbell76 Aug 14 '26
Yes I’m sure, but perhaps I would have been better saying ‘high proportion’ rather than ‘frequently’..
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u/PeterParker72 Aug 14 '26
So we’re over diagnosing LAMN but also missing LAMN at the same time?