This looks like a great case to get your diagnostic juices running, H&E update at 6pm GMT.

Geoff

?congenital cutaneous Rosai Dorfman

Looks like an intrafollicular RDD, but I don't know similar cases and, the most important, plasma cells poorly found here...so my first thought is of Langherans cell-rich lymphadenoma ( but is a provisional diagnosis...this case is very difficult ).

Glandular congenital lymphadenoma.

I see many dendritic cells, but don't know what do these mean.

My provisional impression is RDD, confenital cases exist. Looking for the 6.00 PM update. 

I think we need cd1a and s100. Differential between rosai dorfman and one of the manu types of langerhans cell histiocytosis

My first thought was RDD as well. S-100, CD68 and CD1a will probably solve this case.

BerEp4 doesn't explain the problem, for me: because it could be a RDD that has diffusely infiltrated dermis , including preexisting follicles.   I think this is a lymphadenoma because of first fig, in which you can see an evident plurifocal follicular profile of the infiltrate, and because of I don't see any plasma cells, so characteristic of RDD...but sincerely I also think I can  be wrong!

My first impression really was cutaneous Rosai-Dorfman disease, but the clinical history militates against this hypothesis. A purely cutaneous Rosai-Dorfman disease, without lymphadenopathy, or preceding lymphadenopathy, is rare, and it is even more rare on forehead. Also, it is generally self-limited, does not last 8 years!

Adamantinoid trichoblastoma (lymphadenoma) with abundant intraepithelial lymphocytes, as Vicenzo suggested, is a good point. Peripheral palisading of basophilic basaloid cells, which can be noted in image 5, is a clue.

I don't think you are wrong Vincenzo... BerEP4 highlighting the peripheral cells makes it lymphadenoma. Very unusual!! 

Nice that we all thought of RDD!!

Wow...difficult case. Vincenzo is probably right!!...but why multiple lesions (and since birth)??

Great case! The IHC does make this into a cutaneous lymphadenoma. These can have varying degrees of atypia/RS like cells within the central pale areas. However, not sure if these can present at birth, or have any syndromic association. Waiting to hear from Richard.

This is a cutaneous lymphadenoma.  Almost a one off case (multiple congenital lesions) but we did find the reference cited by Vincenzo who did very well again.  I also shared the case with Dmitry Kazakov by powerpoint and he agreed.  The pan-keratin stained all the lobules diffusely.  It is unusual to have the spillage of the lymphocytes in to the stroma.  I thought this case made a nice contrast one of the spiradenoma's I had placed recently.  Glad if fooled a few of you.  I would like to acknowledge Dr Anita Nagy and colleagues who made the original diagnosis and kindly shared the case with me.

Great Case! Well done, Vincenzo!!