Case Number : Case 743 - 22 Apr Posted By: Guest

Multifocal superficial basal cell carcinoma

Nested melanoma [i]in situ[/i]

On morphology, favour in situ melanoma. Would do immunohistochemistry though (S100, HMB-45, BerEP4).

Skipping solid groups of basaloid cells attached to the epidermal undersurface showing frequent mitotic figures and peritumoral clefting. Increased mucin between tumor cells results in focal disruption. Melanin pigment can be found in basaloid cells as well as in histiocytes. Peripheral palisading is not well developed.
I think it is multifocal superficial basal cell carcinoma, pigmented type.

Epitelioma basocelular superficial multifocal

Superficial BCC, pigmented. Retraction artifact, skip lesions, stromal changes, and a hint of peripheral palisading. Not a melanocytic lesion.

The cells in Fig.3 appear vesicular and epithelioid in appearance wirh prominent nuclei, a feature not observed in BCC.

Of course BCC can show any number of differnent phenotypes (including epithelioid cells). I favour a slightly odd melanoma like nested pattern of superficial BCC but very easily confirmed with absence of S100/melanA and positive expression of BerEP4 with completely negative EMA. The absence of pagetoid spread is very much against bowen's (clonal / pagetoid variant) and melanoma in this case. Having said that I think I have also seen exceedingly rare pagetoid cells in superficial BCC. Looking forward to seeing the answer - nice case.

One way or the other I would rule out nested melanoma first by IHC.
Does the BCCS show pink prominent nucleoli? I do not know it, I favor it does not.
About the apoptosis, well, I don't know either, but theoretically it can be abolished in both cases when bcl-2 and or p53 are overexpressed.
About cleft formation, subepidermal, well, I remember some papers from Human Pathol from around 2005-6 stating the issue as a marker for melanoma, but do not know if the concept is still holding.
So, as you can tell, there's a lot of ignorance on this side, but I still think of melanoma in situ when checking the pics.

Incidentally, there is some exchange of letters about the matter in the last Modern Pathology issue, referring to Dr. Kutzner description of nested melanoma in situ as an entity with epithelioid features and no pagetoid srpead. Unfortunately, access to us, USCAP members, is shutdown due to technical issues and have no more details.
Very interesting case.

Kutzner et al. (2012) described a lesion that is not an in situ proper melanoma but a superficial spreading melanoma, at this moment I have to say: oops!
Looking forward to being surprised with the DX.

Great comments by Dr. Mejia..

[size=4]Pigmented superficial BCC.[/size]

[size=4]- Low-power clustered nesting pattern, lichenoid infiltrate, retraction artifact favors superficial BCC,
- A number of nests [top right photo, right-hand nest] show apparent 'eyeliner' sign with sparing of basal keratinocytes. This would weigh against in-situ MM, but raise the differential Dx of SCC in situ. There is also transepidermal nest elimination, which seems exceptional in sBCC.
- High power image shows palisading against a flat supporting BM [best seen at the left edge of the -separation cleft], that would additionally support a BCC/SCC neoplasm and disfavor Merkel or MMIS.
- Absence of significant lentiginous or intraepidermal pagetoid scatter would be rare in Bowen's or primary MMIS.[/size]

Very nice case, very interesting discussion.
The left side nests with the minimal palisading, clefting against the basement membrane favors BCC, superficial pigmented type.
When I look to the right side nests with the lack of palisading, the presence of vesicular nuclei and prominent pink nucleoli, I feel I can not R/O large nested melanoma in situ. So, if am confronted with this, I will definitely do S100/MelanA first to exclude melanoma. Challenging...
What about a remote possibility of a collision tumor, both superficial BCC and large nested melanoma in situ !!!!!!!!!!!

About collision tumor I have seen somewhere an abstract by Dr. Kutzner, I guess, about a "trichoblastomelanoma", not that this case fits the description but is an interesting possibility, I have not seen one ever in my life, but...

[color=#1C2837][font=arial, verdana, tahoma, sans-serif][size=4]Superficial basal cell carcinoma[/size][/font][/color]

Superficial and pigmented basal cell carcinoma.

Wow! I am thrilled by the number of comments and their excellent quality. Although this is a pigmented multifocal BCC, [i]in situ[/i] melanoma for the many reasons detailed above is an excellent differential diagnosis. However the multifocality, retraction artifact, fairly uniform basaloid cell population, absence of any interest in the overlying epidermis all favor BCC. I do not believe that any immunohistochemistry was done on this case.
[b]Next week I will be moving to live in France and will be out of contact with the web for a few days until I get my new computer. Iskander will be looking after my days for a week or so.[/b]

Thank u so much Dr McKee, wish u a pleasant life in France

Merci pour votre constants enseignements, Dr. McKee. Je vous souhaite tout le succès possible dans votre nouvelle adresse.

Pigmented superficial basal cell carcinoma.

Thanks Dr. McKee for sharing your expertise, experience and knowledge. I wish you the best of moving experiences, fortunately internet will allows to the privilege of contact with you from any corner in the world.

[url="https://docs.google.com/file/d/0B7f20oWJtHDndFREckZxQ3ctZTA/edit?usp=sharing"]https://docs.google.com/file/d/0B7f20oWJtHDndFREckZxQ3ctZTA/edit?usp=sharing[/url]

This link above takes to a picture I have saved from the Kutzner et al paper on nested melanoma published in Mod Pathol [url="http://www.ncbi.nlm.nih.gov/pubmed/22388759#"]Mod Pathol.[/url] 2012 Jun;25(6):838-45
That's why I thought of it as a probably-possibly-maybe-not-so-sure nested melanoma, I miserably flunked
Dr. Kossard from Australia published a letter in Mod Pathol last ink oozing issue April 2013 stating that, well OK, there are some nested melanomas out there, he signed before as a nevoid melanoma in situ, perhaps, a novel recently identified aberrant nevi pathway. Anyway, just for the sake of not feeling depressed for the missed target.