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.
Multiple Bilateral Vesiculobullous Lesions on the Lower Extremities—Diagnosis. Arch Dermatol. 2003;139(2):215-220. doi:10.1001/archderm.139.2.215-d