Patient selection: possible pseudoxanthoma elasticum without characteristic skin lesions
Site selection: flexural skin or scar
Site exclusion: hypertrophic scar or keloid (do not contain as many elastic fibers)
Special stain: Verhoeff-van Gieson and von Kossa stains
The diagnostic finding is the presence of clumping and fragmentation of elastic fibers in the middle and deep dermis (reticular dermis).
Interpretation:
• The presence of diagnostic changes supports the diagnosis of pseudoxanthoma elasticum.
• The absence of the finding does not exclude it since it may be site and observer dependent.
• The more sites that are sampled the greater the chances of finding the feature.
• A skin biopsy can also be helpful in identifying disorders like solar elastosis that may be clinically confused with the skin lesions of PXE.
Performance:
• The change shows a low sensitivity but high specificity.
• Testing for gene mutations in ABCC6 may be more cost effective for the diagnosis of PXE while a skin biopsy allows consideration of disorders in the differential diagnosis.
