If histologic examination detects the following, cutaneous vasculitis is confirmed: Infiltration of the vessel wall by inflammatory cells, resulting in disruption and destruction of the vessel wall Intramural and intraluminal fibrin deposition (fibrinoid necrosis) Extravasation of red blood cells Nuclear debris (leukocytoclasis) Direct immunofluorescence staining is needed to check for IgA, IgM, and IgG and complement deposition in and around the vessel wall, which suggests an immune complex-mediated process, a myeloid or lymphoproliferative disorder, or other neoplastic disorder, especially in adults.