Cutaneous vascular deposition of C5b-9 and its role as a diagnostic adjunct in the setting of diabetes mellitus and porphyria cutanea tarda
Complement Membrane Attack Complex
Porphyria Cutanea Tarda
Granular and homogeneous deposits of C5b-9 in vessels, along with homogeneous deposits of immunoglobulin within the blood vessels, are characteristic immunofluorescence findings in patients with DM and PCT. In regards to potential mechanisms of C5b-9 deposition, decreased metabolism of C5b-9 due to glycosylation of CD59 in the setting of DM and activation of complement by irradiated porphyrins in PCT are proposed. The extent of C5b-9 deposition suggests that this complex may play a pathogenetic role in the evolution of microvascular injury in patients with DM and PCT.