Case Number : Case 2797- 26 March 2021 Posted By: Dr. Richard Carr

Verrucous carcinoma. 

KA mosaic staining with p16 low ki67

I vote for KA too. 

en plaque?

Sadly my opinion was given in the information provided! Apologies for this I suspect it's a new member on the dermpathpro team. I could not give a definitive diagnosis but favoured a follicular hyperplastic / pseudoepitheliomatous process akin to a lichen planus-like keratosis. I think these are not uncommon on the lower legs of females and can be seen as reactions to seborrhoeic keratosis and it's interesting regarding the history of similar sounding lesions on the legs. Keratoacanthoma en-plaque is a reasonable suggestion. The IHC steers us further away from carcinoma I think. Verrucous carcinoma is a minefield for diagnosis and it usually boils down to extended clinical course with the penny taking some time to drop but I suspect it's over- and under- diagnosed in equal measure. The lesion was fully removed by C&C (in this specimen) and patient given an open appointment to return if they develop new or recurrent lesions.