Subcorneal pustular dermatosis an immnohisto-pathological perspective

Subcorneal pustular dermatosis (SPD) represents a chronic, relapsing sterile pustular eruption, involving the trunk and flexoral proximal extremities. A 54-year-old female presented with recurrent, flaccid pustules measuring several millimeters in diameter, on normal and mildly erythematous skin of the groin and submammary areas. Biopsies for hematoxylin and eosin (H&E) examination, direct immunofluorescence (DIF) and immunohistochemistry (IHC) analysis were performed. The H&E staining demonstrated typical features of SPD, including some damage within dermal pilosebaceous units subjacent to the subcorneal blistering process. DIF revealed strong deposits of immunoreactants IgG, IgM, fibrinogen and complement/C3, present in a shaggy pattern within the subcorneal disease areas; in focal, areas of the basement membrane junction and in focal pericytoplasmic areas of epidermal keratinocytes. IHC revealed strong positivity to HLA-DPDQDR, mast cell tryptase, CD68, and ZAP-70 in the subcorneal inflammatory infiltrate, and surrounding dermal blood vessels. Myeloperoxidase was also positive. Positive staining with the anti-ribosomal protein S6-pS240 at the edges of hair follicles and sebaceous glands subjacent to the subcorneal blisters was also noted.

We conclude that this disorder may have several components in its etiopathology, including a possible restricted immune response and a possible genetic component; these possibilities warrant further investigation.