Routine hematoxylin-eosin staining of the biopsy specimen showed a subepidermal blister with a mixed infiltrate of numerous neutrophils and eosinophils. Because of these findings, an initial diagnosis of linear IgA dermatosis was considered. There was no evidence of small vessel vasculitis in the biopsy specimen to support a diagnosis of HSP. Direct immunofluorescence, however, revealed scattered granular IgA deposits in superficial blood vessels and heavy fibrin deposition in the upper dermis, which confirmed the diagnosis of HSP.

During the first few days of hospitalization, our patient experienced severe abdominal pain, which responded well to intravenous steroid therapy. His blood pressure levels were still normal, as were the results of multiple urinalyses. His joint swelling and skin lesions began to resolve 4 days after admission.