Monicccaalmost 5 years ago

“Half-Half” Blisters

A 66-year-old man presented with an acute pustular eruption. On examination, an annular rash with multiple blisters was seen on the patient's trunk; the blisters contained both clear and yellow fluid. He had no associated cutaneous or systemic symptoms, and there was no facial or mucosal involvement. Examination of a biopsy sample taken from a representative blister revealed a subcorneal vesicle and other features characteristic of a subcorneal pustular dermatosis. Direct immunofluorescent staining showed IgA deposition in the superficial epidermis. Subcorneal pustular dermatosis is a chronic pustular dermatosis that frequently affects the flexures of the trunk and limbs. The face and mucosal surfaces are usually spared. The lesions typically have the appearance of “half-half” blisters, with half of each blister containing pus and half containing clear fluid. The blisters eventually coalesce, giving rise to annular and serpiginous arrangements. Unlike acute generalized erythematous pustulosis, which may have a similar appearance, subcorneal pustular dermatosis is not drug-related. It is usually idiopathic, but in a subgroup of patients IgA deposition can be seen with the use of direct immunofluorescence, and it is thought that this phenomenon represents an overlap with IgA pemphigus. An association with IgA monoclonal gammopathy and myeloma has been reported. In our patient there was no evidence of an associated dyscrasia. Once the diagnosis is made, the treatment of choice is dapsone, but in this patient hemolytic anemia developed after its introduction. Although eruptions of this type do not always respond to glucocorticoids, there was a good therapeutic response in our patient. Source: nejm.org