A unique case of intra-epidermal neutrophilic dermatosis-type IgA pemphigus presenting with subcorneal pustules.

Background: While subcorneal pustular dermatosis-type IgA pemphigus shows subcorneal pustules, intra-epidermal neutrophilic dermatosis (IEN)-type IgA pemphigus is characterised by pustule formation throughout the entire epidermis.

Objective: We analysed an unusual case of IEN-type IgA pemphigus showing subcorneal pustules.

Methods: Indirect immunofluorescence, immunoblot analysis, auto-antibody-specific ELISAs, and double-labelling immuno-electron microscopy were performed.

Results: IgA antibodies bound to the surface of keratinocytes distributed throughout the epidermis were detected by indirect immunofluorescence. IgA from the patient's serum failed to react with COS-7 cells expressing desmocollins (Dsc) 1, 2 or 3. IgG or IgA antibodies against desmogleins 1 and 3 were also found to be absent by ELISA. Double-labelling immuno-electron microscopy using an anti-Dsc monoclonal antibody showed localisation in the desmosomes, while IgA from the patient's serum was found in non-desmosomal regions.

Conclusions: The patient in the present study most likely suffers from IEN-type IgA pemphigus.