Case Number : Case 2931 - 30 September 2021 Posted By: Saleem Taibjee

There is alternating parakeraosis/orthokeratosis with irregular acanthosis and few other changes in epidermis. I wondered about PRP juvenile type but the flexural involvement is some what unusual clinically.

Would be interesting to see other thoughts?

Alternating parakeratosis and hyperkeratosis are seen only in horizontal direction and not in checkerboard pattern. Acanthosis and papillomatosis are a bit excessive for the diagnosis of PRP. I think that this could be an inflammatory linear verrucous epidermal nevus (ILVEN) if it clinically fits.

Actually I agree with Saman that there are histological features of PRP.  The parakeratosis and orthokertosis do alternate both vertically and horizontally, and there is some fusion of adjacent rete ridges.  The papillomatosis is rather more than is normally seen in biopsies of PRP, but that may be a feature of the site of the biopsy, which I presume was taken from the foot.  As Saman says, flexural involvement is not usual in the various forms of juvenile PRP.  I think is is unlikely that this is ILVEN as the history suggests that there is symmetrical involvement.

Too papillomatous for PRP. ILVEN is histologically a better option, for me. But I’m thinking about some other...

Interesting dialogue...

We discussed this case at MDT, and the favoured clinical diagnosis was eventually Progressive Symmetrical Erythrokeratoderma. The literature indicates that some patients have an identified mutation in loricrin, genetic testing is awaited on our patient. The limited descriptions of the histology in the literature indicate hyperkeratosis with papillomatosis and acanthosis. Parakeratosis is not really mentioned, although it does seem to be present in our case. Clinically this doesn't really fit for ILVEN which is a mosaic disorder, often in a Blaschkoid distribution. PRP doesn't usually show this degree of papillomatosis, and also didn't fit particularly well with the clinical features.

BW Saleem

I was thinking about some variant of ichtiosis, but this is really an unknown chapter for me....