Case Number : Case 2619 - 21 July 2020 Posted By: Uma Sundram

This is a superficial shave biopsy which doesn't get to the bottom of the lesion.  It's a bit like trying to name everyone in a room by looking through the keyhole, an exercise fraught with danger!  Nevertheless, I see hyperkeratosis overlying acanthotic epidermal downgrowths which look neoplastic rather than reactive i.e. not prurigo nodularis.  The downgrowths show peripheral palisading, but no retraction artefact or mucin.  There are also small horn cysts.  I think this may be a solitary trichoepithelioma.

What about a fibrous papule with follicular induction?

Trichofolliculoma

I like the comment about the keyhole! We are called upon to engage in this exercise every day as practicing dermatopathologists. I often post cases like this, to see what others would do if confronted with this scenario. I did favor a small trichofolliculoma. I like FP w follicular induction as well. The clinician wanted a second opinion, which is why getting other opinions on cases like this is a good idea.

Fibrous papule was my first thought but I suppose a glancing blow of of trichofolliculoma could be a possibility too. Agree with Richard's and Uma's comments.