Case Number : Case 2444 - 14 November 2019 Posted By: Saleem Taibjee

First thing I would do is a PAS stain and look for hypha (tinea incognito).

neutrophilic spongiosis

PAS stain to rule out dermatophytosis

Many neutrophils and capillaries on tip of dermal papilla make me think of a psoriasis ( maybe drug resistant). 

If dermatophytosis is ruled out by PAS stain, pityriasis rubra pilaris should be considered in the differential diagnosis as there's irregular acanthosis and parakeratosis alternating with orthokeratosis

Psoriasis and Dermatophytosis are great differentials, I´ll suggest nutritional deficiency aswell, there is a little bit of vacuolar degeneration and a few necrotic keratinocytes so we should think on drugs Rx aswell. Clinical correlation.

Last figure:

looks like a little vacuolar interface as Victor mentioned. There appears an increase of interstitial mucin. What are the  perivascular cells? Some are lymphocytes but many are not. Mast cells?

sir once we something like mucin in dermis I would like to rule out dermatomyositis

however there would be other clinical parameters and lab support

You guys are good! Yes this was tinea incognito. The PAS stain and striking clinical appearance is shown below, before and after treatment with oral antifungals.

Nice case, Dr Saleem, many thanks. 

sir wonderful

common things are common

Great teaching case!

Yes wonderful case