Case Number : Case 4149 - 15 Dec 2022 Posted By: Saleem Taibjee

There is a large, sub-corneal split, but without the associated neutrophilic infiltrate that would be expected with bullous impetigo, fungal infection, or Sneddon-Wilkinson disease.  The inflammatory infiltrate is mixed, but eosinophils and plasma cells are visible.  I am wondering about pemphigus foliaceous or a drug-induced pemhigus-like problem.

Any chance it might be bullous pemphigoid with re-epithelialization?

The advanced age, history of large blisters and eosinophils in the infiltrate are suggestive of bullous pemphigoid with re epithelialization. Is the patient a diabetic on any of gliptin group of drugs ? DIF will be decisive. ELIZA for anti BP 180 and anti BP 230 is also available now.

20 hours ago, sfwenson said:

Any chance it might be bullous pemphigoid with re-epithelialization?

I did consider that possibility, but was put off by the amount of inflammation still present under the epithelium.  I would have thought things might be a bit quieter if this were re-epithelialisaiton.

Why not an ischemic damage, like acroangiodermatitis, in a venous insufficiency?

A subcorneal split with mixed inflammatory cells, including eosinophils, but lacking acantholytic floating keratinocytes. So I'm not favouring a pemphigus. Also 'large blisters to legs and torso' I think makes pemphigus less likely since these blisters easily rupture and are usually ulcerated/crusted.

I think there are reactive changes in the basal keratinocytes directly underneath the split- perhaps they are dividing to re-epitheliaise the epidermis. So I favour bullous pemphigoid with reepithelialisation.

Yes, very well done. This is a recent case of bullous pemphigoid. Common things being common. The direct immunofluorescence was confirmatory.

This is an important pitfall - re-epithelialisation giving rise to the false impression of a more superficial level of blistering. I have seen such cases cause great confusion, especially when there is always a risk of false negative IMF.

It emphasises the importance of the clinician trying to select a fresh/new blister to biopsy.... ' the lives of lesions'.

Happy Christmas everyone!

Saleem