A skin biopsy specimen obtained from an early pustular lesion showed focal subepidermal and intraepidermal vesicle formation, a dense neutrophilic infiltrate involving the entire dermis and extending into the subcutaneous tissue, and prominent leukocytoclasis and fibrinoid changes in the walls of small blood vessels. Direct immunofluorescence studies showed strong staining with IgG and IgA in the superficial and middermal vessels and with fibrinogen in the superficial dermal vessels. Special staining of the tissue sections did not demonstrate any bacterial or fungal organisms.
Pustular Plaques on the Face of a Patient With Renal Failure—Diagnosis. Arch Dermatol. 2004;140(11):1393-1398. doi:10.1001/archderm.140.11.1393-f