Case Number : Case 781 - 14 June Posted By: Guest

Epidermal induction by DF.

Bowen's disease induced by dermatofibroma.

Is this a combo of Bowen disease and dermatofibroma ,trichodiscoma,or dermatomyfibroma.Or is it a recurrent Bowen disease with scar of previous excision?
Need history.

I don't feel this is dermatofibroma because there are sweat gland ducts within the lesion itself, a feature not expected to find in a dermatofibroma. And epidermal hyperplasia extends beyond the limits of the underlying fibrous lesion (upper right of picture #1).
Superficial located fibrocytes of a dermatofibroma are known to act as follicular papilae and induce folliculosebaceous structures from the above epidermis, sometimes with follicular germinative appearance that simulates a true basal cell carcinoma. I don't believe dermatofibroma has the capability of induce Bowen's disease.
Like Dra. Maria George, I favor a recurrent Bowen's disease over the scar of a previous biopsy.

Definitly there is Bowen's disease. As regards the underlying dermis I agree with Maria's idea

I reported this as a dermatofibroma with subtle clonal and pagetoid bowen's. Really this is a very typical sclerosing late DF but I can see the confusion as we have discussed before selected images can be misleading. But certainly scar's would not have preserved sweat glands and the absolutely typical epidermal hyperplaisa in image lower left (from a different cross-section to image top left) and the beautiful collagen entrapment typical of DF lower border and periphery on the left side in the low power. As another point of interest elastic fibres tend to be preserved in DF (and DFSP for that matter) but not in scars. In this old sclerotic stage I cannot see the elastic too well in these particular images. I made a note of the immunos as follows: Focal moderate p16 (a little dissappointing); p53 ?lost but difficult be because subtle lesion; Ki67 not particularly helpful. The Bowen's extended out beyond the DF in two blocks and I assumed was just another chance collision of two common diagnoses. This is the first time I have seen the association.

Too late to jump in on this one (sigh). Agree of course. Classic DF and Bowen's disease as a collision tumor. My observations to support the final DX:

1. The Bowen's disease is asymmetric and only appears in the right side of the epidermis (top left photo), and has border with the benign epidermis just right of photo center. There is basal layer sparing (eyeliner sign) and pagetoid involvement of adjacent epidermis (bottom right photo) near the junction with adjacent normal epidermis at the photo left border.

2. DF: Classic 'basaloid follicular induction' resembling superficial basal cell carcinoma actually seems very rare in the DFs that I see....despite what dermpath texts suggest. The sharply angulated 'delicate' reticulated SK-like epidermal induction with hyperpigmentation, and/or subtle basaloid palisading (as seen in bottom left photo) is often the [i]only [/i]clue of an underlying DF in many unfortunate and suboptimal [i]'rule out DF[/i]' shave biopsies.

[i](Imagine a superficial shave of the area in the bottom left photo...one that doesn't include the telltale sclerosis or fibrocytes at the deep edge of the photo....try confirming that as a DF...ouch! A good reason to encourage clinicians to avoid shaves for a rule-out-DF case). [/i]

The sclerotic area is expansile...it is pushing everything around it... including epidermal contour, encased adnexa and adjacent deep reticular dermis and long rete peg (on far left edge)... away from the center of the sclerotic zone in the top left photo.