Histopathology of pseudoxanthoma elasticum and related disorders: histological hallmarks and diagnostic clues.

Among ectopic mineralization disorders, pseudoxanthoma elasticum (PXE)-a rare genodermatosis associated with ocular and cardiovascular manifestations-is considered a paradigm disease. The symptoms of PXE are the result of mineralization and fragmentation of elastic fibers, the exact pathophysiology of which is incompletely understood. Though molecular analysis of the causal gene, ABCC6, has a high mutation uptake, a skin biopsy has until now been considered the golden standard to confirm the clinical diagnosis. Although the histological hallmarks of PXE are rather specific, several other diseases-particularly those affecting the skin-can present with clinical and/or histological characteristics identical to or highly resemblant of PXE. In this paper, we will summarize the histopathological features of PXE together with those of disorders that are most frequently considered in the differential diagnosis of PXE.