Case Number : Case 3027 - 11 February 2022 Posted By: Dr. Richard Carr

Endophytic SK with clear cell changes?

The tumour lobules at the base of the horn show peripheral palisading, an eosinophilic basement membrane and pale to clear cells. I think that this is a trichilemmomal horn.

benign squamo proliferative lesion with foci of trichilemmal differentiation

What the hell is going on here? A verrucous SK with trichilemmal differentiation ? Or a verrucous sebaceoma? Favor the first, of course: too many and prominent horn cyst. 

11 hours ago, vincenzo said:

What the hell is going on here? A verrucous SK with trichilemmal differentiation ? Or a verrucous sebaceoma? Favor the first, of course: too many and prominent horn cyst. 

For me also either verrucous SK with trichilemmal differentiation or Trichilemmal horn. 

I also thought a horn from a seborrheoic keratosis. I guess it does look tricholemmal but I didn't run IHC on this particular case. Maybe just a mimic.