Surgical oncology in melanoma vs Mohs surgeon

[ehlersdanlos]

Is there a difference in the procedures/surgeries performed by a surgical oncologist specializing in the removal of melanoma versus a Mohs surgeon? I know that the career trajectory/path to getting to these fellowships are different and rooted in different focuses, but just wondering how the scope of practice might differ in this regard.

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[sore eye asses]

The two fields are vastly different and incomparable really. As a mohs surgeon you'd rarely/never be performing procedures to excise the type of melanoma that would be treated by surg onc. If anything, for critical areas requiring tissue conservation, surg onc could just act like a modified mohs surgeon and have surg path read frozens (something I doubt they have much experience with, and maybe just a few cases like this in experienced hands). I don't think this happens too often, but maybe the mohs guys could expound more.

 

[Winged Scapula]

I'm not aware of any Moh's surgeons trained to do sentinel node mapping and biopsies or lymph node dissections which is part of the management of melanoma; this is standard in surgical training.

 

[asmallchild]

I'm not aware of any Moh's surgeons trained to do sentinel node mapping and biopsies or lymph node dissections which is part of the management of melanoma; this is standard in surgical training.

This is usually the split. If you are going to send the patient for sentinel node mapping anyway (I have a discussion with the patient in the intermediate risk zone of 0.75 - 1cm and let them decide; I usually do not give them a choice once > 1cm in depth), I usually refer the excision as well to the surgical oncologist.

There are dermatologists / Mohs surgeons who choose to remove invasive melanoma either via wide local excision or Mohs. If via wide local excision, this portion is likely similar to what the surgical oncologist does. If via Mohs, you act as the surgeon and the pathologist during the surgery (this is not standard in surgical training)

 

[Winged Scapula]

This is usually the split. If you are going to send the patient for sentinel node mapping anyway (I have a discussion with the patient in the intermediate risk zone of 0.75 - 1cm and let them decide; I usually do not give them a choice once > 1cm in depth), I usually refer the excision as well to the surgical oncologist.

There are dermatologists / Mohs surgeons who choose to remove invasive melanoma either via wide local excision or Mohs. If via wide local excision, this portion is likely similar to what the surgical oncologist does. If via Mohs, you act as the surgeon and the pathologist during the surgery (this is not standard in surgical training)

Agreed - with in situ/thin melanomas without worrisome features, a dermatologist is well within their scope of practice to handle it as SLNB is not standard of care/necessary.

Our OP is presumably not knowledgeable enough about the management of melanoma or would not have asked the question; I wanted to point out that the issue was not necessarily one of "cosmetic areas" requiring Mohs but rather what we're dealing with. Even here most of the Mohs guys end up sending melanoma and other SST defects to plastic surgeons when the defects are large enough/cosmetically important areas.

 

[asmallchild]

Agreed - with in situ/thin melanomas without worrisome features, a dermatologist is well within their scope of practice to handle it as SLNB is not standard of care/necessary.

Our OP is presumably not knowledgeable enough about the management of melanoma or would not have asked the question; I wanted to point out that the issue was not necessarily one of "cosmetic areas" requiring Mohs but rather what we're dealing with. Even here most of the Mohs guys end up sending melanoma and other SST defects to plastic surgeons when the defects are large enough/cosmetically important areas.

Also true, a lot of this is also dependent on practice location.

In my area, most of the Mohs surgeons are so busy (or risk averse) that any melanoma with an invasive component (and even quite a few in-situs) get sent out to the surgical oncologist for wide local excision +/- SLNB. Furthermore, whether seeing the dermatologist or the surgical oncologist, many patients will request closure by plastics (that's not to say the surgical oncologist or the dermatologist couldn't close the defect. It's just what the patient demands sometimes.)

 

[deltamed]

Is there a difference in the procedures/surgeries performed by a surgical oncologist specializing in the removal of melanoma versus a Mohs surgeon? I know that the career trajectory/path to getting to these fellowships are different and rooted in different focuses, but just wondering how the scope of practice might differ in this regard.

Mohs is an outpatient specialty and they do 99% non-melanoma skin cancer (mostly BCC and SCC) and for melanoma mostly stage T1a lesions that do not need sentinel node (a few will pair with another specialist to do stuff in the OR but its rare).

As far as I know most surgical oncologists dont "specialize" in melanoma except perhaps a few highly niche academics. Most of the T1b+ lesions are cared for by general surgery (if on trunk) or ENT/plastics (in head neck region). Thats because if it's metastasized all over most people would agree they are no longer a surgical candidates.

Of note on another subject, T1b+ lesions are the vast minority of all lesions. Most early lesions are actually excised by general dermatology.


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[reno911]

So much of how this is handled is Mohs surgeon dependent. I think only 10-20% of Mohs College members do Mohs for melanomas. Lots of Mohs surgeons don't treat them because it's just more hassle. I do it it because, in my opinion (and I realize there is some dissent on this issue), that the complete margin control that Mohs provides is the best way of obtaining local disease control.

There is a common misconception (in my view) that tissue sparing is an important feature in these cases. It really isn't. I do Mohs because it is the best way to clear the tumor. The tissue sparing is a natural consequence of the fact that you don't have to take large margins in all directions.

So, for tumors that don't meet criteria for SLNB, I just do Mohs and with rare exceptions, I perform all the reconstructions.

For tumor that meet criteria for SNLB, I offer the pt two options:
1- They can go see a surg onc and have an SNLB only (followed by lymphadenectomy if indicated). Then they see me after and I treat the melanoma w/ Mohs.
2-They can go see surg onc and have and SNLB + excision all performed at the same time.

Most choose the latter option, because it is logistically easier and for most tumors below the neck the advantage of Mohs over a wide excision is probably not very high. As an aside, in a handful of cases where the patient takes the first option, when they see the surgeon for consultation, they are talked into option 2. I normally don't fight it unless I think the tumor is likely to have a large in situ component (in those cases, they're just going to send it to me when there excision has MMIS at the margins, and that's more unpleasant to deal with).

 

[ehlersdanlos]

Thanks everyone for the replies so far. They have been very enlightening, as Winged Scapula correctly presumed that I don't have much knowledge yet on the subject matter.

Forgive me if my next question is an equally foolish question, but here goes nothing: why is it that dermatologists/Mohs surgeons aren't trained to do SLNB? To me, it seems like it would make sense since a more comprehensive treatment or work-up of Melanoma might involve SLNB...

 

[asmallchild]

Thanks everyone for the replies so far. They have been very enlightening, as Winged Scapula correctly presumed that I don't have much knowledge yet on the subject matter.

Forgive me if my next question is an equally foolish question, but here goes nothing: why is it that dermatologists/Mohs surgeons aren't trained to do SLNB? To me, it seems like it would make sense since a more comprehensive treatment or work-up of Melanoma might involve SLNB...

That's actually a pretty good question.

My guess is that SLNB is something that has traditionally been done in the OR setting which is not typically where most dermatologists perform their surgeries. (Although a cursory sweep of Pubmed seems to indicate this can be done under local anesthetic as well)

The next question is when to stop. If the SLNB comes back positive, do you go back for the full lymph node dissection? Are you fully prepared to handle the adverse effects of this kind of surgery?

In the end, dermatology training is tight enough trying to fit in general derm, dermpath, pediatric derm, dermatologic surgery, cosmetic dermatology, etc into 3 years. I just don't think there's enough interest among dermatologists to fit this into the curriculum. I wonder if there are some Mohs fellowships out there that work SLNB into the curriculum? (Mine didn't. Although I suspect you run into the same issue. It's tight enough trying to fit in a minimum caseload for Mohs, get you regular exposure to all the reconstructive options, get you exposure to cosmetic dermatology, etc in one year. After all, the vast majority of skin cancers that you will take care of as a dermatologist are fortunately non-melanoma skin cancers.)

If your interest in melanoma is that keen (i.e. you want to do the bigger cases and not the in-situs), I think surgical oncology is probably the better fit.

 

[MOHS_01]

I'm not aware of any Moh's surgeons trained to do sentinel node mapping and biopsies or lymph node dissections which is part of the management of melanoma; this is standard in surgical training.

In Europe it's routine for a dermatologist to do this apparently

not here. Not it. Nope.


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[MOHS_01]

Oh, btw, I'm happy to let others deal with nodal disease; we have our plate full with trying to keep them from getting to the point of needing a SLNB.


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[MOHS_01]

...and, FWIW, I do not personally perform micrographic surgery on any invasive melanoma for a couple of reasons and will only do a modified "slow Mohs" on LM/MIS (wherein the debulking is submitted for staging and margins are processed separately for margin control with micrographic mapping). If a simple primary closure is not possible without undermining, reconstruction is delayed until margin determination. It is read by dermpath that I trust and billed as standard excision.

That's just how I approach it.


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[Winged Scapula]

In Europe it's routine for a dermatologist to do this apparently

not here. Not it. Nope.


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True.

The dermatologists there have a lot more general surgical training as well but you can really get yourself into trouble with deep nodal dissections.

 

[Winged Scapula]

...and, FWIW, I do not personally perform micrographic surgery on any invasive melanoma for a couple of reasons and will only do a modified "slow Mohs" on LM/MIS (wherein the debulking is submitted for staging and margins are processed separately for margin control with micrographic mapping). If a simple primary closure is not possible without undermining, reconstruction is delayed until margin determination. It is read by dermpath that I trust and billed as standard excision.

That's just how I approach it.


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That's how the guys here that I'm familiar with handle it as well (so must be good practice )

 

[asmallchild]

...and, FWIW, I do not personally perform micrographic surgery on any invasive melanoma for a couple of reasons and will only do a modified "slow Mohs" on LM/MIS (wherein the debulking is submitted for staging and margins are processed separately for margin control with micrographic mapping). If a simple primary closure is not possible without undermining, reconstruction is delayed until margin determination. It is read by dermpath that I trust and billed as standard excision.

That's just how I approach it.


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What are your reasons if you don't mind my asking?

The more surgeons I talk to, the more I find them shying away from invasive melanoma (either via Mohs or wide local excision) and even performing Mohs on in situ lesions. I'm starting to think there's some experience/wisdom that I need to glean here

 

[MOHS_01]

What are your reasons if you don't mind my asking?

The more surgeons I talk to, the more I find them shying away from invasive melanoma (either via Mohs or wide local excision) and even performing Mohs on in situ lesions. I'm starting to think there's some experience/wisdom that I need to glean here

Big one -- medicolegal. The accepted standard is not micrographic surgery and there are people who would line up around the block to testify that you are not practicing standard of care -- despite whatever Zitelli article you hold up as evidence. Ha. Beyond that, there is significant disagreement as to whether or not MM is a contiguous disease process or demonstrates significant field effect. I am not convinced that anyone has significantly -- much less definitively -- demonstrated that it is a contiguous disease process, and in the absence of that micrographic surgery's comparative advantage is very limited. Sure, you still are examining a greater percentage of the margin -- but if it is not a contiguous disease process this matters less. Perhaps more consequentially, however, is that many (most) of our peers believe this to be the case... and swimming upstream with an uncertain argument is poorly defensible.

Many shy away simply for the medicolegal risk.

 

[Tamahawk]

What are your reasons if you don't mind my asking?

The more surgeons I talk to, the more I find them shying away from invasive melanoma (either via Mohs or wide local excision) and even performing Mohs on in situ lesions. I'm starting to think there's some experience/wisdom that I need to glean here

Good discussion.

Based on the (very informal) show of hands at the most recent ACMS meeting, only around 10-20% of the audience members volunteered that they do Mohs for melanoma of any type. That said, the data to support Mohs for MMIS, LM type are quite strong, mainly from Zitelli's group and the Mayo group. Most of the trainees from these programs (and of the second generation Zitelli programs) do perform Mohs for melanoma upon going into their practice, largely because they have a lot of exposure during fellowship and feel comfortable.

I personally believe that Mohs (with MART-1) is superior to standard WLE for melanoma in situ on the head and neck almost entirely due to the fact that you check a greater percentage of the margin. The slow Mohs/"square technique" advocated by the U. Michigan group also achieves the same ends. In both techniques, what matters most is that the pathologist or Mohs surgeon must feel very comfortable with their training on such evaluations. I've had the opportunity to take part in both methods, and IMO neither is superior from a histologic standpoint. However, Mohs with IHC has the advantage of being performed in 1 day versus some of the square procedures which may drag on for days-weeks.

Having said this, there are a few things that I do that make me feel like Mohs is often the best option for head and neck MMIS:
1) My initial layer for MMIS is typically 6mm around the clinically obvious lesion. IMO, the primary goal for Mohs'ing LMs is to ensure full assessment of the margins to ensure against recurrence/persistence, moreso than tissue sparing in the standard sense for NMSCs.
2) I only Mohs MMIS and superficially invasive LMs (less than 1mm vreslow and no mitoses) that have been adequately sampled (not just a small sample of a larger lesion). These superficially invasive melanomas tend to be invasive centrally only, with the edges being radial/ in situ growth. On these thin melanomas I often take closer to 1cm margin on my initial layer. These thin melanomas have minimal baseline risk of metastasizing, and since I often take the standard 1cm clinical margin anyway, I do not think it would be easy to get sued for this (after all, you would be excising with the standard recommended clinical margin). Mohs has a higher chance of clearing the peripheral MMIS in these cases, which should decrease recurrence risk.

At the end of the day, I don't fault any Mohs surgeon who doesn't feel comfortable doing Mohs for LM, as comfort level has a lot to do with exposure during training. However, for those groups who have done a lot of cases, the cure rates and mortality appear to be at least equivalent to WLE. I luckily had a lot of exposure to it, so I do it. There are many other things I didn't have exposure to in training (especially complex eyelid margin cases) that I therefore feel uncomfortable doing, so I do not do these things. In short, we all tend to do things we are comfortable with and should probably not do things we are not comfortable with.

 

[MOHS_01]

^^^. Agreed. There were guys doing LM on frozens prior to the advent of immunostaining... that I may or or may not have been quite familiar with... and the discordance rates between frozen interpretation and paraffins were unacceptably high. If I had proper exposure and experience with the technical aspects of doing IHC in the Mohs lab I would be comfortable with that - for LM / MIS, but since I have not - and rarely do I ever get an adequately biopsied LM (for staging purposes I mean) - I still do things the other way... and it is shocking the percentage of times that invasion is identified in the debulking excision.

The most contentious talk I've ever given was to the general medical community on skin cancer including the appropriateness of Mohs following a question on LM. Ignorance abounds... and is rather fixed.


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