Richard Carr

Histopathologists & Dermatopathologists: Do you give completeness of excision on epidermoid cyst removal specimens. If so why? If not why not?
Poll on X: x.com/RACARR51/sta...

RAC9313. F50s. Thigh. Skin tag. Basic case #Dermpath

I appreciate there is a single atypical mitotic figure but you should note multinucleation. When a multinucleate cell divides it's mitosis will be atypical. I reported it as a poroma. One more image here (nice coffee-bean).

RAC3910: x4 more images at request of @rishiagrawal.bsky.social

Sensible. I'll "attach" them to the main post!

RAC3910 M60s. Dorsal foot warty lesion. ?VW ?SCC.#Dermpath @iyengarish.bsky.social

Recurrent PAK2 rearrangements in poroma with folliculo-sebaceous differentiation - PubMed Recurrent fusions involving the PAK2 gene in all analysed poroma with folliculo-sebaceous differentiation in this study confirms that this neoplasm represents a separate tumour entity distinct from YAP1::MAML2 or YAP1::NUTM1 rearranged poromas.

RAC9309 My Dx: Poroma with folliculo-sebaceous differentiation, probably PAK2 fusion. pubmed.ncbi.nlm.nih.gov/37199682/

RAC9309: M80s. Lower back, ?SEBK, shave. H&Ex4 #Dermpath @rishiagrawal.bsky.social

RAC9306: EVG & Commentry. Then MSH6 (loss) & PMS2. Advised referral to medical genetics to rule out Muir Torre Syndrome (familial cancer associated syndrome).

RAC9300: IHC as requested @rishiagrawal.bsky.social

Posting p16 & p53

Yes reactive (mosaic for p16, peripheral graded or wild type matching Ki67 distribution in lesions were basal / germinative cells a dominant). Some benign lesions have >proliferation c/w p53 expression. I believe this is a case in point.

RAC9306. EVG & Discussion. I thought this was a mitotic sebaceoma / sebaceous adenoma. MSH6 & PMS2 requested. So far been sceptical about clear-cut Seb Ca & MTS. See a lot mitotically active lesions erroneously called carcinoma.

RAC9306: IHC Montages, EVG & Comment Summary to follow

4me no overtly worrying features for malignancy. Yes no applique. Sebceomas can by highly mitotic (like pilomatrixoma). Benign adnexal lesions are often patchy weak mosaic (in my studies p16 tends to be much higher in Seb Ca). Additional IHC/EVG/BerEP4/EMA & comments posted.

RAC9300. Lower powers. @rishiagrawal.bsky.social #dermpath

RAC9300. F80 ish. Neck. ?SK ?AK

RAC9306: IHC here p16, p53, Ki67 @rishiagrawal.bsky.social These are representative.

RAC9306. M80s. Nose. SCC. #dermpath @rishiagrawal.bsky.social

Great to be in Cape Town. Wayne Grayson introducing the XLIV symposium of the ISDP = International Society of Dermatopathology.

👍 Broekaert...Kazakov. Squared-Off Nuclei and "Appliqué" Pattern as a Histopathological Clue to Periocular Sebaceous Carcinoma: A Clinicopathological Study of 50 Neoplasms From 46 Patients. Am J Dermatopathol. 2017 Apr;39(4):275-278. PMID: 28323778.
Applique is characteristic but not specific IMO.

Yes. Read discussions with @rishiagrawal.bsky.social For me a reactive PATTERN rather than a single entity and not a neoplasm. Relatively common and usually overlying bony prominences. I report at least one or two a year.

I often do EVG in such cases if I think it will affect management. Completely circumscript borders with no entrapment we regard as supporting in situ and more likely to consider "watchful waiting".

Yes FSCC. mainly in situ. In UK pT1 low risk are not followed up unless margins are close. I think I also favoured focal invasion. Margin was positive but I may have said "watchfull waiting may suffice". I'll check on that.

This lesion lacks neutrophil microabscesses and more importantly no signs of regression. With IHC highly aberrant null/weak only p53 FSCC-KA-LIKE is favoured.

Agreed. Mosaic p16 but highly aberrant null +/- weak only p53. Favours FSCC-KA-like.

RAC9302: What you need to asses such lesions. p16 & p53 - you should be able to work out which is which.

There is certainly a little mucin in the stroma. The edges of the keratinocytes have a hazy blue appearance but not convincing mucin pools. I'll post IHC now.

RAC9302 M80s Presternum. ?SCC #Dermpath @rishiagrawal.bsky.social

This was an SCC arising in actinic keratosis (4 more images here). There was tumour in a small muscular vessel in the deep dermis I interpreted as a vein. It's uncommon but can happen in SCC as well as otherwise typical KA and even in BCC. I find most SCC are de novo or follicular type.