Case Number : Case 1756 - 20 February - Dr Limin Yu Posted By: Guest

'Short and Sweet' here is your Spot Diagnosis Case from Dr Limin Yu to get your week off to a great start.

Geoff Cross - DermpathPRO Projects

A tricking case: half Sweet Syndrome ( sub epidermal blister and dermal neutrophilic infiltrate ) half Subcorneal Pustular Dermatosis/Sneddon Wilkinson ( pustular sub corneal component ). My spot is Sneddon Wilkinson, but maybe an association...

Assuming that clinical manifestation may be intact pustules, IgA pemphigus and miliaria crystallina are my favorite hypotheses if non-intertriginous areas are affected, and subcorneal pustular dermatosis of Sneddon-Wilkinson if the flexor aspect of the proximal lower limb is the site of the lesions.

I think it is predominately subepidermal. Neutrophil mediated. Seems localized to right thigh. Sweet is a possibility but would have expected more dermal neutrophils, a clinical of nodules and plaques that may have surface vesiculation which is not the case.  I am thinking more in the line of localized neutrophil mediated BP. Prebullous stages may show spongiosis and intraepidermal vesicles which can explain the focal intraepidermal component here. This is my theory and waiting for DIF images !! I mean with neutrophil mediated BP, the anti p105 and the anti 200 types

Although I dont see eosinophils, I would add bullous drug eruption to the differential.

Tricky case....my impression was that the subcorneal pustule is the main inflammatory reaction pattern and the subepidermal oedema is secondary. Hence would consider d/d of subcorneal pustular reaction including IgA pemphigus, AGEP etc....need more clinical info.

I too think that the subcorneal pustule is the main pathology. Would favour IgA pemphigus and other differentials. Clearly, DIMF and clinical picture needed.

Agree with all the above differentials above. But given the localised reaction- would consider impetigo (grams?). Herpes is also a possibility depending on clinical (though fail to see any tzanck cells in these sections). Other possibilities include an insect bite reaction. CPC is a must +- DIF.

This is an AGEP. Agree with all the above differential diagnosis.  You guys are awesome!!