Case Number : Case 2721 - 10 December 2020 Posted By: Saleem Taibjee

Pigmented Bowen disease. clinical and histological 

The cells involved in the Pagetoid spread have a rather bubbly cytoplasm.  I wonder if this is In-situ sebaceous carcinoma, but of course at this anatomical site pigmented Bowen's disease would be far more likely.  IHC needed.

Pagetoid Bowen's disease. Also, extamammary Paget's disease has rarely been described on unusual location other that perineal region. IHC will help. 

Sebaceous carcinoma in situ. 

Sebaceus carcinoma x pagetoid Bowen´s x extramammary Paget disease. IHQ

Pigmente Bowen disease

Yes, well done, this is pigmented and pagetoid Bowen's. I picked out the most pagetoid areas for the Spot Diagnosis, but there were more conventional Bowen's areas also (see below). It is a recent case where it was nice to have the clinical and dermoscopic images to correlate with the histology. The pigment is quite striking on the dermoscopy, but notably there is no true pigment network, and the vessels are arguably 'glomeruloid', all in keeping with Bowen's. Of course, a histological clue that this is Bowen's and not melanoma with pagetoid spread is that there is preservation of the basal layer which rims the pleomorphic cells, and that any apparent nesting is not actually junctional. At a higher power, one is able to discern the desmosomal attachments. I agree that the cells are a bit bubbly, but the cells lack the indented/crenalated nuclei for true sebaceous differentiation, and this would be an odd anatomical site for sebaceous carcinoma. Hence I did not run immunos, and indeed it might be difficult to conceive an immunopanel which would reliably distinguish Bowen's from sebaceous carcinoma. I do not have access to adipophilin at our lab. I have wondered about using PRAME as a surrogate for sebaceous differentiation, but have been discouraged by others' more extensive experience (e.g. Klaus Busam).

BW, Saleem

Very nice, thanks Saleem.

Beautiful case, tks for sharing. SCC in situ

Tks f sharing, Saleem.