Step I carcinoma insitu malignant? or pre-malignant?

[teehees]

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So according to uworld QID 564:

Adenocarcinoma insitu (lung) is Malignant?

But hold on, wasn't the hold idea behind carcinoma vs carcinoma insitu that the latter was pre-malignant? ie not malignant?

 

[zhopv10]

Malignant is based on the potential for invasion. Carcinoma in situ (DCIS for example) has high potential for invasion of left untreated, hence why it is treated aggressively upfront. Benign tumors are tumors without the potential for invasion. The idea behind the in situ is it hasn't gone through the BM yet. There is also I suppose a place for "pre malignant" like a polyp or something but that term is not synonymous with benign. And really it is just a qualifier for the "level" of malignancy, but it is still malignant. One way to maybe he'll remember it is to think of the cancer cells themselves. What's the difference between the cytology of a DCIS say and a T1N0M0 breast cancer? Not much, except invasion into surrounding tissue.


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[zhopv10]

*edit: I know your question was more rooted in the pre-malignant vs malignant not the benign I just brought they in for reference/contrast. Hopefully they helps.


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[Transposony]

So according to uworld QID 564:

Adenocarcinoma insitu (lung) is Malignant?

But hold on, wasn't the hold idea behind carcinoma vs carcinoma insitu that the latter was pre-malignant? ie not malignant?

That's because you can't be sure if it has invaded until a complete resection is done and the tissue examined histologically.
So, unless proven otherwise (by histology) it is considered invasive.

Wikipedia
Carcinoma in situ is, by definition, a localized phenomenon, with no potential for metastasis unless it progresses into cancer. Therefore, its removal eliminates the risk of subsequent progression into a life-threatening condition.
One of the most dangerous forms of CIS is the "pneumonic form" of BAC of the lung, which can require extensive surgical removal of large parts of the lung. When too large, it often cannot be completely removed, with eventual disease progression and death of the patient.

 

[okokok]

Agree with @zhopv10 - carcinoma in situ's are malignant (as implied by the word "carcinoma" itself - check out FA 2015 p234, it gives the nomenclature for malignant vs benign tumors). A carcinoma in situ isn't premalignant, just "pre-invasive" (FA 2015 p232)

 

[ninjaman22]

Carcinoma in situ: malignant but hasn't invaded through the basement membrane
Carcinoma: malignant and has invaded through the basement membrane

 

[teehees]

Thanks for that guys. It was just a long-standing concept of mine that one was pre malignant which I guess was wrong.

That's because you can't be sure if it has invaded until a complete resection is done and the tissue examined histologically.
So, unless proven otherwise (by histology) it is considered invasive.

The question I'm referring to included a biopsy with histology indicative of in situ but I guess you're trying to say there could be parts that are invasive?

Your wiki article also states that it has no potential for metastasis unless becomes a carcinoma. I guess that's wrong too unless malignant doesn't mean cancer

 

[zhopv10]

Ya I think the phraseology of "no potential for metastasis" is more just saying that if it hasn't broken through the BM it couldn't have metastasized (can't invade lymph etc yet). So it is a more mechanical definition. When talking about a cancer that is malignant because it has the potential to invade and is this a malignancy it is talking more about the biology (rapid division, differentiation, ability to invade BM, etc.). I.e with DCIS the cells are pre carcinoma, they haven't had enough time to invade and do their thing yet, but if you left it it would almost certainly turn into a carcinoma and metastasize. It has the tools all it needs is time. Now take a fibroadenoma, there is not a chance that it will invade, it has zero potential to do so.


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[okokok]

So according to uworld QID 564:

Adenocarcinoma insitu (lung) is Malignant?

But hold on, wasn't the hold idea behind carcinoma vs carcinoma insitu that the latter was pre-malignant? ie not malignant?

Just got a UW question that made me remember this thread (q id 1753). The question is saying that dysplastic change is non-malignant and reversible. It is also saying that high-grade dysplasia is synonymous with carcinoma in situ, which was what you originally thought. It says that dysplasia isn't irreversible til it breaches the BM. So idk, maybe you're right.

 

[teehees]

I thought I remembered a question on Rx very similar to the Uworld one that stated it was benign. With the same diagnosis. But Rx doesn't have a search function..

I'm willing to go with the above and uworld though