Dr. Cora Humberson discusses the important prognostic factors when diagnosing malignant melanoma.
we come from a variety of backgrounds at this meeting and dr patterson did a terrific job of outlining the clinical and historical context and the uh new technologies that are available. And we'll explore those more in depth as we go along. But our next speaker is dr cora. Anderson and cora is an anatomical and clinical pathologist. Dramatic pathologist who has been on the faculty of Scripts clinic for several years and she's a coordinator in dramatic pathology for the department of pathology at scripts. And she's going to cover for us the history of pathologic findings uh for melanoma as well as prognostic indicators. So cora, europe. Thank you. Good morning. I have uh let's see, There we go. I have no conflicts of interest to report. My topic is the pathology of melanoma as well as classification and prognostic indicators. So that's uh that's a big topic and we'll go somewhat quickly and try and hit all of the high points more of a logic classification of malignant melanoma. Most melanomas fall into these four categories. There are lots of rarer variance of malignant melanoma. This isn't even a complete list. But they're important to be aware of because they can mimic other malignant tumors as well as benign tumors. So these are potential pitfall lesions and I'll show um I'll show examples of all four of these and some examples of these other variants. First off superficial spreading malignant melanoma is the most common morphological subtype it occurs and skin that's intermittently sun exposed usually such as the trunk and it's characterized by an insight to component which has a pageant toyed scatter, which I'll show you in a moment. It's the subtype of melanoma which the A. B. C. D. Rule is most useful. Asymmetry, irregular border and color and diameter. That's usually greater than six millimeters. The most common driver mutation and superficial spreading malignant melanoma Is the beer f. v. 600 e mutation. So these are all from our files. This is an example of a superficial spreading malignant melanoma and a 42 year old woman on the back. It was eight millimeters in diameter and it checks all the boxes for the A. B. C. D. Rule. It's asymmetric. No matter what uh plane you draw a line in. You can't get this to be a mirror image. It's irregular and its border with notches and in color. And here's a little nodule er component as well. This is the histology of that lesion showing the classic pattern of the pageant. Toyed or buckshot scatter of the insight to component which at higher power you can see those malignant melanoma sites are extending throughout the entire thickness of the epidermis. Mhm. This sucks 10 demonstrates this very nicely. It's a nuclear stain and it highlights the fact that those malignant melanocytes are at all levels of the epidermis. The second most common morphological subtype is linked to go malignant melanoma. And it occurs in skin with high cumulative sun damage. So you get a lot of solar blastocysts accompanying the lesion, head and neck are common sights and usually in an older population. These lesions usually are occurring in a field in which there are lots of solar linkage chinese. So that can make evaluation of margins somewhat problematic. The fact that there's high accumulative sun damage is reflected in the fact that there is a high mutation burden in these types of tumors. And here's a nice example of Alinta go malignant melanoma. You can see all of this solar e blastocysts replacing much of the dermis. This is in the neck of a 75 year old woman. You can start to see the insight to component very patchy and irregularly spaced. The Sox 10 immuno stain demonstrates that link indigenous pattern of intra epidermal spread. So not much in the way of uh Padgett toyed scatter like in the superficial spreading melanoma. Uh classically this type of melanoma. The insight to component will also extend along add next cell structures. Um This particular lesion had Apache like annoyed inflammatory infiltrate and that's not uncommon. So if you get a sample that you think may be a like annoyed benign keratosis and severely sun damaged skin, Take a look at the dermal epidermal junction because this inflammation might be hiding Alinta go malignant melanoma Sampling is very important in these lesions. The first shave biopsy of this tumor. I showed only three tumor cells but in the exceptional specimen. Uh we ended up with the final stage of a final Breslow thickness of 1.3 mm and this particular lesion had both perry neural and intramural invasion, which is not uncommon in this type of melanoma. Okay. Third type modular melanoma, who definition of melanoma exclusively on the vertical growth phase, which means it can be a melanoma without an identifiable insight to component. If an insight to component is present, it's usually not in the epidermis. Uh next to the tumor, you'll find the insight to component overlying the modular component only and you can expand the A. B. C. D. Rule for modular melanoma to include E. F. G for an elevated firm nodule that's quickly growing. This doesn't have a unique genetic profile. Uh It has um a stage for stage, it's the same prognostic features for Nigel or melanoma as for superficial spreading melanoma. This is an example from our files, a 92 year old woman who had a rapidly growing large lesion on her shoulder. It was 5.6 mm in Breslow thickness and here's uh cross section of that tumor on low power showing you the exotic modular growth pattern. Uh This lesion was also ulcerated, so a great deal of hemorrhage within it and a higher power view of the edge demonstrates that lack of insight to component in the epidermis adjacent to the lesion. This is also a nice example demonstrating a new modular melanoma um with a socks 10 side by side with the H and a demonstrating that lack of an insight to component in Nagy alor lesion and finally acro lint. Indigenous melanoma is defined by its location. Uh It's more commonly in the acro sites on the heel than the palm. If it's sub lingual, the fingernail is involved more often than the toenail and um the thumb and great toe are involved more often than the remaining nail units. And this has led some to postulate that it may be micro trauma that's associate that's involved in the ideology of mackerel indigenous melanoma because it's not associated with a UV exposure. It has a low mutation burden. Um not too often as be raft. The driver mutation, There are usually structural chromosomal changes and um and copy number of variations. Here's a recent example. We had uh this man had trauma to his nail approximately 20 years ago. The entire nail was ripped off. Uh the Nail did grow back and there were no problems for about 18 years. And then in 2019 there was another episode of trauma. But this time the nail did not completely grow back but a red uh Nigel developed in the nail bed. And this was an actual indigenous malignant melanoma uh to orient you on the amputation specimen. This is the distal failings the bone at the base here. This is the nail plate which you can see abruptly stops here, The um are the invasive portion of the tumors. Attenuating and destroying the nail bed. So this nail plate isn't being formed over the lesion. This particular example of mackerel indigenous melanoma didn't have a particularly linton Guinness insight to component was more of a pageant toyed. But you see that variation. This was a particularly aggressive tumor. It was 3.3 mm in thickness, very atypical cytology, high metabolic rate and four of the five sentinel lymph nodes were positive for tumor. So now we'll go to some of those unusual variants that can lead to pitfalls in the diagnosis of melanoma, knee void melanoma. It's an uncommon variant. It can look like a nevis both on the histology and the clinical presentation. So the A. B. C. D. Criteria I don't usually apply and the clinical outcome has the same prognostic features as other subtypes. The term ni void may make it sound like it's uh not as aggressive but it's just to indicate that it can resemble a nevis clinically and histological E So this is a very good example we had from about 10 years ago now. So the image isn't as terrific as I'd like. Uh the histology I put beside the knee void melanoma and nevis and just to demonstrate that it can look almost exactly on low power like a nevis. This is the knee void melanoma on that gentleman's elbow and this is a benign nevis. For comparison. Neither one of them demonstrates any insight to activity. Both of them give the appearance of maturation on low power. Mhm. But when we looked at this lesion on higher power, we noticed there were metallic figures deep in the lesions. So that was the tip off. This particular one also had very little in the way of psychological tibia. Here's a small group of melanocytes that are larger have coarser chrome autumn than their neighbors. So that was a very subtle feature. This is the type of lesion that can feed you to the lions. You don't want to be this guy right here. So how do you make that diagnosis of the void melanoma? An immuno history chemical piano can help you. Um This is the Hmb 45 stain on that lesion. Hmb 45 reacts with pre Melanie soames. And in benign nev I uh Melanie stones are lost as the melanocytes to send deeper into the dermis. So A characteristic staining pattern of a benign nevis with HMB 45 is a uniformly faded pattern with most of the reactivity occurring superficially and this knee void melanoma. The fading pattern is not uniform. So if you draw a line across the lesion, you'll find some clones which are not producing mill anus owns and some that are so that is a non faded pattern which is a red flag. Yeah. The other red flag we had was may I go back one slide because I I clicked ahead too quickly. Thank you. Uh The key 67 immuno stain was helpful, all these brown dots indicate melanocytes there in growth phase for a benign navassa growth phase of much less than 5% is characteristic. But this had this lesion had a growth rate Much higher than 5%. And I think more importantly than that they're melanocytes and the growth phase which were deep in the lesion. So that's a red flag. Um since this was 10 years ago we didn't have some of the immuno stains available to us that we have now. Um P 16 is one of those you can use this in a lesions such as um any void melanoma. To help with the diagnosis. P 16 is a tumor suppressor protein encoded by C. D. K. N. Two A which will recognise as one of the genes in the hereditary melanoma syndrome. Um It's not uh you must use it as part of an immuno hist o chemical panel, not as a stand alone because in my experience about 10 to 15% of melanomas will lose P 16 expression. The reported range is much greater than that. So there's quite uh quite a bit of variability with the P 16. This is a very good review and meta analysis if you're interested in um in P 16 use in melanoma uh frame is one of the newer antibodies used in the evaluation of malignant melanoma. And uh The vast majority of conventional melanoma will express frame about 90%. However, about 10% of Nev I will also express frame. I'm gonna talk more about praying in just a moment. But going back to our knee, void mel Anoma. How did we establish that diagnosis then? Since we had very few immuno stains to help us with that? We performed comparative genomic hybridization on that lesion and that demonstrated numerous gains and losses in several chromosomes characteristic of malignant melanoma that indicated genomic instability. And the final diagnosis on that small pink popular was non ulcerated melanoma 1.2 mm in thickness. Now a little bit about praying since it is newer in on the field. Uh the name comes from preferentially expressed an urgent in melanoma. This is a very good paper on frame. Um, there are several other tumors that express praying, but they usually don't come into the differential diagnosis of melanoma. And there are a few normal tissues which will also express it. But as I indicated earlier, it has very good sensitivity and specificity uh, for uh, for melanoma and there are a few pitfalls and I'll demonstrate some of those. And there are small also some potential uses for it uh, that have come in very handy in recent experience for us. Uh, this is a lesion I recently used preying on. It's a 48 year old woman. She had a 10 by nine millimeter irregular pap. You'll that was occurring inside a tattoo on her arm. So there was a lot going on in this lesion here. There's an area that looks like it's likely nervous here was tattoo. And then there was this ulcerated lesions suspicious for melanoma. Higher power view of each of those areas, showing you the portion of the lesion that looks psychologically bland and appears to be maturing likely than Leavis. And the area which was suspicious for um invasive melanoma. And then the tattoo. Yeah. The sox 10 immuno stain reacted with all the melanocytes. So that was helpful to show the melanoma and say to portion of the lesion. Um but it doesn't distinguish between the nevis and what is likely invasive melanoma in this region. Yeah, P. 16 really wasn't a value either because you can see both. Um the nevis and the melanoma still express P. 16. So that didn't help to differentiate. But the cream did do a good job of differentiating between the benign and malignant portions of this lesion and that helped in measurements. So here you have the frame reacting with the melanoma in sight tube. It's not reacting with the nevis. And in the area where I was suspicious for invasive melanoma, you can see the cream staining positively. So I measured from uh to this point. So the final diagnosis of this lesion was an ulcerated melanoma at the site of a Nevison tattoo. The Breslow depth was 0.4 mm And uh t. one b. Because of the ulceration. Um crime can also be helpful evaluating margins and severely sun damaged skin such as Linda Go Malignant Melanoma. Uh and I used it in this case an 84 year old man who had a large pigmented lesion on his cheek area of high cumulative sun damage, which you can see demonstrated with all this solar blastocysts. This was a melanoma in sight to lend to go malignancies subtypes. So that's demonstrated in the H. And E. Here And then the Sox 10 show that classic pattern of linkage in the spread of the lesion with very little upwards scatter and involvement of the Milan a sites. Uh sorry, add next cell structures by the melanocytes. So the difficulty can come in evaluating surgical margins in this type of skin. This is a peripheral surgical margin of the exceptional specimen. And here you can see the melanoma insight to trickling along and it can be really difficult to decide. Where does that melanoma in sight to end And just the background of solar milan a site. Oh sis uh and this person severely sun damaged skin begin based on the socks. I would say it's somewhere in this region. But it would be nice to have some supporting evidence of that. And in this case, that's what the prime provided the primes reacting with the melanoma insight to. And then you have this abrupt change with no brain positive nuclei. So that distance was between one and two, which was relatively close. I just want to point out that in some instances depending upon where you what clothes you have on the tighter you use, you can have non specific staining of sebaceous uh material and that's what's standing here. These sebaceous glands. This isn't indicative of invasive melanoma. So that was a pretty close margin. And the surgeon decided to go back and do a re excision. So again, you can see that sun damaged skin. This is the old peripheral surgical margin. This is the new peripheral surgical margin. Mhm. The Sox 10 showed an increase in the density of melanocytes but it doesn't isn't particularly suggestive of melanoma insight to but it was very reassuring to get that crane stain that showed absolutely no melanocytes staining. So this gave some reassurance that we have several more millimeters of clear surgical margin. In that case, if you're of a certain age, you may remember the peanuts cartoons and every fall lucy would offer to hold the football for charlie brown so he could kick it and she always pulled it away at the last minute and he got that breath knocked out of him. And this is a cartoon. I think of every time a new antibody comes along for melanoma, you get really excited. You want to use it on everything. But it's not a magic bullet and you don't want to depend upon it solely because you will get the uh breath knocked out of you if you do. And this is an example, showing showing how prime can be sometimes misleading. This lesion was from a 55 year old woman, her right lower abdomen. The clinical history of self care versus an atypical nevis. It's showing an atypical intra epidermal milan acidic lesion. That's very Seiler inflamed, lots of pigment loss. And the Sox 10 showed a pattern classic for melanoma in sight too superficial spreading subtype. The frame that was completely negative. So it's just a cautionary tale. A negative frame does not equate with benign lesion and a positive frame does not unequivocally mean a a malignant lesion. So you have to use your panel approach. Just like all the other antibodies we have cream is no exception. So that was a lot of immuno. His. So chemistry a moment to brush away some cobwebs. I'll show you something completely different. Um this spider lived in my garden for the whole year of 2020 and she had a lot of egg cases. This is one of them right down here. It almost looks like a leaf and part of the plant she was big about 2cm. This was a hatching um of the uh spiders. And you see the web is a little denser in that area. And then when the duke burned off they get active. Okay. And then at night towards evening. Yeah, they would huddle together and maybe you can advance that for me because I I can't get to it. It's there it is there they're all had to link together in the evening. Now going back to business at hand. Desmond plastic melanoma. Another one of those melanomas that can potentially be a pitfall because it can resemble scar both clinically and histological e because it's a tumor that occurs in high uh sun damaged skin. The mutation burden is high and neurotrophic is um is common and that leads to a higher chance of local recurrence. Here's an example from our files in an 81 year old man. You can see that background of solar Linta goes the low power of you. It's not particularly alarming. There's a lot of solar l last Asus, there's a lot of inflammation. But when you look at this lesion on uh intermediate power you start to see a sailor uh dermis. And on highest power you pick up malignant individual slightly spindle cells. This particular lesion had a great deal of neuro trumpism. So there's actually more tumor in this nerve than there is um out in the dermis and the sox 10 is demonstrating for you that perry neural invasion, the intramural invasion and even perry vascular uh involvement. This is a nice article. Review article and uh lead to go malignant and dismal plastic melanoma. So how are things changing in the classification of melanoma? They're moving towards a system that includes the genomic attributes. This is a modified table from the who textbook on skin tumors and you can peruse this at your leisure. But one of the takeaways from it is the high mutation will burden of lego malignant and desmond plastic melanoma as opposed to um tumors melanomas that have a lower cumulative sun damage such as superficial spreading staging and reporting. I think in the interest of time we'll skip over the pathology report. The eighth edition of the A. J. C. C. Staging system has been out for three years now. So this table you can look at later. It highlights the changes and we'll go to the prognostic factors. The most powerful prognostic factor remains the Breslow thickness. Um When you have a complex lesion, it's helpful to take multiple samples because a shave biopsy or single punch may not give you A true characterization of the tumor. This is one such tumor. It was on the abdomen of an 80 year old man. It had been slowly changing over time. The shave biopsy just showed melanoma in sight. To the first punch biopsy showed melanoma in sight to and a lot of regression. Another area that had more model pigmentation demonstrated melanoma on site to and invasive melanoma as well as a band of pre existing nevis. And this next slide shows how uh the sox 10 and Hmb 45 differ and can uh hmb 45 can help you in choosing the area to measure Breslow depth the nevis is not staining with the HMB 45 um as it is in the socks tense. You'd want to measure this tumor at this point rather than at this point. And then the money was in the nodule er component where it demonstrated a tumor of two in thickness. Baracus lesions can be difficult to measure. Sometimes I'll give two measurements uh trough and peak and say that the lesion is at least this thickness but no greater than this thickness. Beware of vertically oriented um tumor. It may represent melanoma in sight to extending along and add next cell structure such as this case. That negative image is an ekeren duct and the melanoma and site is extending along that. So you wouldn't want to measure here and call this an invasive melanoma. We still report my topic activity. Although it's not used in the sub classification of melanoma ulceration is ulceration is a poor prognostic feature um level for level uh tumors which are ulcerated have a lower disease free survival and overall survival at sight of carotene stain. Can help show you that that alteration where it is present and how extensive it is tumor infiltrating lymphocytes. Um There's evidence on both sides favorable unfavorable. The same is true for regression. Although I would say probably the sum total this is more likely a favorable prognostic indicator than unfavorable lymph vascular invasion. Also a poor prognostic feature. You want to look not only in the within the tumor for lymph vascular invasion but also and neurovascular bundles around the tumor, particularly if there's inflammation. So this is a higher power view of this area in this area. There were at least two fosse of tumor within lymphatic spaces. You can see that here and here. But remember the pitfall benign nev I can sort of pooch into lymphatic spaces. So milana sites within a lymphatic space don't always equate with invasive melanoma. And then finally perry neural invasion which can be found not only in lent to go malignant melanoma and desmond plastic melanoma, but also in superficial spreading and other all other types of malignant melanoma. I want to thank all of the dermatologist who send us tens of thousands of cases each year. Um All of those cases were from our files and also our team of dramatic pathologists here at Scripps Clinic for sharing all of their cases. And then one final thought um there were a lot of Jaw dropping moments in 2020. And I'm wishing everybody more of this. 2021. Thank you for your attention. Thank you cora. That was an excellent presentation. We have uh one we're at time but we have one brief question we are being asked is frame available in house at scripts. Or do you or is it a send out. So right now we are bringing the histology service uh in house. We don't have it available now. Um I've used praying from a couple different laboratories and just a few cautionary notes, I would say make sure you always look at the positive control. Um anecdotally. I would say some histology supervisors have told me that it can be a difficult antibody to work with. So you always want to make sure that that control is working and that you have a good idea of whether it's standing strongly or weakly. And you want to match that with your test uh with your delusional tissue. All right, thank you very much. Excellent presentation, appreciate it.
