Case Number : Case 1734 - 19 January - Dr Arti Bakshi Posted By: Guest

Sorry for slightly later than normal Daily Spot Posting, here we have a lovely case from Dr Arti Bakshi.

Cheers, Geoff Cross - DermpathPRO Projects

Thinking of porokeratosis ptychotropica with possible secondary candidal superinfection. 

The intracorneal neutrophils is what made me think of candidal superinfection as it can not be explained in the context of porokeratosis alone. 

Verrucous porokeratosis, a proposed terminology to encompass porokeratosis ptychotropica and other descriptive terms of the verrucous variant of porokeratosis involving the gluteal cleft.

Agree with porokeratosis either verrucous or ptychotropica as my colleagues suggested. I have read that the clinical appearance of the lesions is important to differentiate the entities (verrucous is always hyperkeratotic and can be located in other areas appart from the buttocks while ptychotropica is always located on the latter and is not hyperkeratotic). So based on these I favour verrucous in this case

My first thought was of Porokeratosis, too. But after the first img I completely changed track...This because of my unknowledge of Porokeratosis Ptychotropica ( or Verrucous Porokeratosis ). Now I feel pretty sound what my Colleagues argue about this lesion. And agree with Mona that there is probably a Candida infection overlap to explain many neutrofils scale crusts. But I have a question to the experts: why not a flexural seborrheic dermatitis? 

1 hour ago, vincenzo polizzi said:

My first thought was of Porokeratosis, too. But after the first img I completely changed track...This because of my unknowledge of Porokeratosis Ptychotropica ( or Verrucous Porokeratosis ). Now I feel pretty sound what my Colleagues argue about this lesion. And agree with Mona that there is probably a Candida infection overlap to explain many neutrofils scale crusts. But I have a question to the experts: why not a flexural seborrheic dermatitis? 

You will not see the typical cornoid lamelle in seb dermatitis Vincenzo, but u will c parakeratosis with neutrophil and exudate centered on follicular ostia. We have here typical cornoid lamellae with underlying agranulosis and dyskeratotic cells. 

Ok, Mona. Thank you very much.

Nice case of Porokeratosis ptychotropica. It is important to recognize this entity, as some cases are clinically and even histologically misdiagnosed as HPV infection. I had 2 cases like this, one patient had 30 years of evolution without diagnosis and was treated as Lichen simplex chronicus!!

Well done all!...this is a case of porokeratosis ptychotropica.

The images were posted in the wrong order. the 1st 2 are actually from the satellite lesion, which show typical cornoid lamellae without much inflammation. The rest of the images show significant inflammation (including neutrophilic collections in stratum corneum) and disruption of cornoid lamellae, which lead to an erroneous impression of psoriasis by the referring pathologist. PAS stain for fungal profiles was negative, so most likely the inflammatory changes seen are secondary to friction/trauma, given the site within the natal cleft. As Mona rightly pointed, the dyskeratotic cells are a clue to cornoid lamellae, even in the areas where typical tiers of parakeratosis are not seen. Completely agree with Igor, that these cases are easily missed.This case too has had previous biopsies reported as lichen simplex chronicus!