Case Number : Case 2127 - 3 August 2018 Posted By: Dr. Richard Carr

Fibroepithelioma and foreign body reaction may be to some dermal filler.

I was thinking of something as IgG4-related sclerosing disease, but there are many giant cells and other morphological findings not fitting. So my first spot is "Pulse Granuloma".

CK5 images now added...

Fibroepithelioma of Pinkus with a foreign body granuloma around the keratin of a ruptured cyst

To me, looks like there is a syringofibromatous reaction in the epidermis. Congo red?

Yes this is some reactive eccrine syringofibroadenomatous hyperplasia but the main point is to see the innumerable colloid bodies that extend in to the mid dermis on H&E (highlighted by a pan-keratin or in this case CK5) associated with prominent inflammatory infiltrate. Note the foreign body type giant cells (part of "keratin granulomas").  All these features point to complete regression of a squamoproliferative lesion possibly superficially invasive e.g. actinic keratosis, superficial SCC, KA, inflamed seborrhoeic keratosis etc. BCC may regress fully leaving colloid bodies too.

Nice case!