Case Number : Case 1987 - 17 Jan 2018 Posted By: Iskander H. Chaudhry

Melanocytes singly and in nests, few melanophages and dermal lymphoctic infiltrate- Lentiginous junctional nevus AKA 'Jentigo'

Jentigo could be a good spot, but...Not sure these are melanocytes, without IHC. I think this is an actinic keratosis, until proven otherwise...

Pigmented actinic keratosis (background solar lentigo). Agree should do MelanA as there might be the odd nest of melanocytes but may all just be pigmented AK mimic of melanocytic lesion.

Agree with Dr. Carr. Pigmented acantholytic actinic keraosis. The last micrograph shows possible atypical melanocytes. May be there is actinic melanocytic hyperplasia. Sox-10 may help.

Pigmented AK

Inflamed/irritated/badly beat up seborrheic keratosis? Atypia often seems to be in the eye of the beholder.

Agree with comments above. Need a MelanA, especially with the last image.

On 1/17/2018 at 12:52, vincenzo polizzi said:

Jentigo could be a good spot, but...Not sure these are melanocytes, without IHC. I think this is an actinic keratosis, until proven otherwise...

Ok! The "proven otherwise" should imply a Lentigo Maligna. But sincerely I find this case very difficult to spot!!

In my opinion a pigmented actinic keratosis with dendritic melanocytic hyperplasia, focally nested, of doubtful clinical significance.  Not diagnostic for lentigo maligna (melanoma in situ).

I never used Melan-A to prove one way or the other whether a lesion is a melanoma or not until I read the comments on the usefulness of Melan-A in melanocytic lesions on this website. So I have been trying to use Melan-A to  help me in some cases. I'm no expert on Melan-A. But what I noticed is Melan-A appears to stain strongly a lot of lesions, more than I can recognize on H&E. However, when I also do SOX-10 as control, I noticed that in many lesions, there appears to be a discrepancy between Melan-A and SOX-10 stains. Some lesions look strongly positive with Melan-A like the figures in this case, but the density of the melanocytes is not really increased in the nuclear stain SOX-10. So I'm not quite sure about the whole thing. If I do not see atypical melanocytes in a pigmented lesion on H&E , and I do both Melan-A and SOX-10, most of the times it doesn't change my mind because I'm not impressed with SOX-10 although Melan-A looks quite angry. I would appreciate any comments on this issue.

Hi Anh,

I hope you have a chance to come back to your post because it's a REALLY important issue. I would personally caution on the use of Melan A relative to sox 10 since Melan A does seem to highlight quite a lot more than Sox 10 does. It is probably getting some keratinocytes and there is non specific adhesion to pigment, etc. I think Sox 10 (when it works) is the way to go. That being said, if you feel comfortable working up your melanocytic lesions with H+E alone, go for it! Morphology is often more straightforward than immunos -- the latter often make things very confusing.

7 hours ago, Uma Sundram said:

Hi Anh,

I hope you have a chance to come back to your post because it's a REALLY important issue. I would personally caution on the use of Melan A relative to sox 10 since Melan A does seem to highlight quite a lot more than Sox 10 does. It is probably getting some keratinocytes and there is non specific adhesion to pigment, etc. I think Sox 10 (when it works) is the way to go. That being said, if you feel comfortable working up your melanocytic lesions with H+E alone, go for it! Morphology is often more straightforward than immunos -- the latter often make things very confusing.

Dr. Sundram,

Thank you very much for the comment. I agree H&E is more important. I just started to do Melan-A in the last few months because I'm scared that I miss something after seeing a lot of requests for Melan-A on the website. So far I do not really think the stains really changed my mind on most of the cases when I did both Melan-A and SOX-10. So I just keep Melan-A in the back of my mind whenever I needs a push but I would use it very cautiously.

By the way,  I have learned a lot from the comments of the participants and I'm very grateful to be part of the group.

MelanA is a superstar and never really lets me down - I use it a lot when "speed reporting" on pigmented AKs and solar lentigos with possible mild atypical melanocytic increase. Just remember true melanocytic nests can be seen as a "reactive" phenomenon in lichenoid reactions (may be the case here). Make sure, if you are counting, you only count the cells with complete ring positivity not all the dendritic processes. Provided those rounded nuclear bodies with complete ring positivity are <20 cells / 0.5mm (one high power field) its usually not diagnostic for lentigo maligna. >20 nuclear rings and you are starting to get into the realms of confluence (I'm assuming a flat epidermis of course). When you're not sure admit it and just say something like this. Not diagnostic but subtle lentigo maligna cannot be excluded or subtle basal increase in mildy atypical melanocytes or uncertain clinical significance or even add suggest clinicopathological correlation. Then go home and have a really good nights sleep as no-one died of subtle lentigo maligna!  I wish I did have Sox10 though!