High-frequency (20-50 MHz) ultrasonography of pseudoxanthoma elasticum skin lesions

摘要

Background In most patients pseudoxanthoma elasticum (PXE) manifests with yellowish cutaneous papules and dermal elastorrhexis on skin biopsy. In a small number of cases there are no skin manifestations on clinical examination, and establishing a diagnosis of PXE in such patients is challenging. High-frequency ultrasonography (HFUS) may be of use in predicting skin areas that would yield a biopsy specimen positive for elastorrhexis. Objectives To describe characteristics of clinically visible PXE skin using HFUS, and to evaluate its relevance for diagnosis. Methods HFUS was performed in a cohort of patients with PXE and in controls at a referral centre. HFUS images of PXE skin were compared with those of other conditions. Five operators blind-scored multiple HFUS images of photoprotected or photoexposed skin from patients with PXE and controls. The diagnostic indices (sensitivity, specificity, likelihood ratios, interobserver agreement) were calculated. Results The HFUS changes considered as diagnostic for PXE were primarily oval homogeneous hypoechogenic areas in the mid-dermis. The size of these areas closely matched the extent of the histological changes. The sensitivity and specificity of the diagnostic items and interobserver agreement were high, particularly in photoprotected skin. Dermal hypoechogenicity in PXE could be related to high hydration of connective tissue due to the presence of glycosaminoglycans despite elastic fibre mineralization. Conclusions HFUS provides suggestive images of PXE skin lesions. HFUS should now be studied to determine whether it is a potentially valuable technique for the noninvasive identification of elastorrhexis in patients with PXE in whom skin involvement is clinically minimal or absent. What's already known about this topic? Typical pseudoxanthoma elasticum (PXE) skin changes are yellowish papules and are associated with unique elastic fibre fragmentation and calcification on skin biopsy. High-frequency ultrasonography (HFUS) features of cutaneous PXE have not been reported previously. What does this study add? Noninvasive HFUS examination of the skin of patients with PXE revealed unique echostructure characteristics with oval homogeneous hypoechogenic areas in the mid-dermis. These features may be useful for diagnosis of PXE in ambiguous cases and may aid the choice of skin site for biopsy in patients with subtle or no clinical changes. The hypoechogenic areas were consistent with the presence of localized hydration due to deposits of glycosaminoglycans.