Case Number : Case 1998 - 1 Feb 2018 Posted By: Iskander H. Chaudhry

Erythematous pruritic plaques on the trunk and those on the dorsa of the hands show symmetry. Epidermis shows psoriasiform hyperplasia with patchy spongiosis and eosinophils. Dermis shows perivascular infiltrate with eosinophils. These features suggest a psoriasiform drug rash. Has the patient received beta blockers or terbinafine?

Spongiotic Psoriasiform reaction pattern with eosinophils, not worrisome of CTCL on pathological level. I agree with the possibility of drug reaction. 

Yes, spongiosis and psoriasiform. Eosinophils++. So, a drug reaction remains a distinct possibility. Otherwise, psorisiform eczema. No features of MF.

Dr Richard Carr's comments:

Agree clinical could be CTCL (although hands look quite lichenified). The pathology is eczematous and not worrying for CTCL. Agree drug induced worth considering. If you have more than one biopsy PCR can be helpful and might allay clinical colleagues worries.

Agree with above comments

But sincerely I was thinking of something like erythema chronicum migrans/Lyme disease...This is a very hard case for me.

Congratulation again to the admin team for adding clinical photos when appropriate consent level allows. The images are of excellent quality and makes a significant difference especially in an inflammatory Dermpath case such as this one.

1. I would consider urticarial/pre-bullous/prodromal phase of an immunobullous disease especially bullous pemphigoid first. The protraced course of 18 month without expression of blisters is a bit unusual in my view and DIF can support or exclude this easily.

2. The reactive annular erythemas group is worth consdering if DIF is negative including Eosinophilic Annular Erythema. The gross spongiosis, eosinophil exocytosis and mild superficial perivascular lymphotic infiltrate will be atypical for conventional figurate erythemas including the superficial variant.

3. Drug is possible on histology basis alone but I am not aware of this clinical pattern of cutaneous drug eruption and it is very unlikely in this context.

4. Again neither clinically nor histologically is fits with an insect bite or anthopode assault.

5. Rare causes of other eosinophil rich dermatosis one need to be aware are Wells Syndrome and Eosinophilic Dermatosis of Haematological Malignancy (AKA insectbite-like reactions especially in those with CLL but certaingly not exclusive to this hence renamed lately EDHM). The infiltrate is probably too sperficial for the latter on histology alone. 

Dr Chaudhry's diagnosis:

Based on clinical differentials working diagnosis is cutaneous drug eruption