Case Number : Case 4074 - 01 September 2022 Posted By: Saleem Taibjee

Dermatofibroma. Collagen trapping and epidermal induction are characteristic.

Look like dermatofibroma with overlying basaloid induction and collagen entrapment

Would get a CD34 to exclude Plaque-like CD34-positive dermal fibroma or plaque-like DFSP.

On 05/09/2022 at 19:19, msofopoulos said:

Look like dermatofibroma with overlying basaloid induction and collagen entrapment

Agree. A plaque like DF for me. 

Atrophic dermatofibroma with overlying follicular induction.

Yes, well done, an example of dermatofibroma with striking overlying follicular induction. I resisted to request a CD34 because this really must be dermatofibroma. Follicular induction is well-recognised in DF, and I have also attempted to show the focal lipidisation (penultimate image) and peripheral collagen entrapmen (final image) which are also typical of DF and help to distinguish from other entities such as DFSP.

Over the years I have come to realise that Dermatofibroma on the upper arm/shoulder is something of a special site. DF is often rather atrophic and not at all obvious clinically.

BW, Saleem