Therapy of Pseudoxanthoma Elasticum: Current Knowledge and Future Perspectives

Pseudoxanthoma elasticum veiled as vasculitis: shedding light on an uncommon disorder and an in-depth review of the literature

Pseudoxanthoma Elasticum (PXE) is a rare genetic disorder caused by an autosomal recessive mutation in the ABCC6 gene. It manifests with distinctive clinical symptoms impacting the skin, eyes, and cardiovascular system, along with an elevated risk of cardiovascular diseases. We present a case of a 34-year-old male patient who was initially referred to the rheumatology clinic for evaluation due to suspected large vessel vasculitis. The patient's primary complaint was severe hemifacial pain radiating to the neck and upper limb. Radiological imaging studies unveiled substantial vascular narrowing and collateral vessel formation, prompting further investigation to exclude systemic vasculitis. Intriguingly, the patient also exhibited cutaneous manifestations, which were later confirmed via skin biopsy as consistent with PXE. An ophthalmological examination further revealed the presence of the classic PXE findings of angioid streaks. Given the rarity of PXE and its multifaceted clinical presentation, it can be particularly challenging to diagnose and manage. As such, cases like the one presented here may necessitate a referral to a rheumatologist for evaluation of potential systemic involvement. To provide a comprehensive perspective on PXE, we conducted a systematic review of case reports published in the past decade in English, collected from PubMed, Scopus, and the Directory of Open Access databases. The analysis of these cases will be discussed to shed light on the diversity of PXE's clinical features and the diagnostic and management dilemmas it poses and to facilitate ongoing exploration and research into this intricate condition, ultimately leading to improved care for individuals affected by PXE.

A 21-year-old woman with progressive asymptomatic skin laxity in flexural regions

We describe a 21-year-old woman with progressive asymptomatic skin laxity in the flexural regions.

Pseudoxanthoma elasticum is associated with cardiocirculatory inefficiency

Pseudoxanthoma elasticum (PXE) is a rare, genetic, metabolic disease characterized by dystrophic calcification of elastic fibres in the skin, retina and vascular wall. Data on cardiac involvement are inconsistent. Hence, we aimed to evaluate cardiorespiratory response to incremental cardiopulmonary exercise testing (CPET) in PXE. A total of 30 PXE patients (54.0 ± 11.2 years, 40.0% male) and 15 matched controls underwent symptom-limited incremental CPET. PXE patients presented an impaired peak work rate as compared to controls (84.2 ± 16.0% vs. 94.7 ± 10.4%, p = 0.03) that was accompanied by a lower peak oxygen uptake (in % predicted and mL/min/kg), reduced increments in oxygen uptake per increments of work rate (ΔV´O₂/ΔWR, 8.4 ± 3.0 mL/min/W vs. 11.3 ± 4.9 mL/ min/W, p = 0.02), lower peak oxygen pulse (78.0 ± 12.3% vs. 90.6 ± 19.6%, p = 0.01) and reduced minute ventilation at peak exercise (V´E, 66.2 ± 16.8% vs. 82.9 ± 25.2%, p = 0.02). To summarize, we presently observed impairment in mainly cardiocirculatory parameters, whilst no substantial ventilatory limitation was detected. The potential implications of this finding for PXE management warrant further study.

Targeting ABCC6 in Mesenchymal Stem Cells: Impairment of Mature Adipocyte Lipid Homeostasis

Mutations in ABCC6, an ATP-binding cassette transporter with a so far unknown substrate mainly expressed in the liver and kidney, cause pseudoxanthoma elasticum (PXE). Symptoms of PXE in patients originate from the calcification of elastic fibers in the skin, eye, and vessels. Previous studies suggested an involvement of ABCC6 in cholesterol and lipid homeostasis. The intention of this study was to examine the influence of ABCC6 deficiency during adipogenic differentiation of human bone marrow-derived stem cells (hMSCs). Induction of adipogenic differentiation goes along with significantly elevated ABCC6 gene expression in mature adipocytes. We generated an ABCC6-deficient cell culture model using clustered regulatory interspaced short palindromic repeat Cas9 (CRISPR–Cas9) system to clarify the role of ABCC6 in lipid homeostasis. The lack of ABCC6 in hMSCs does not influence gene expression of differentiation markers in adipogenesis but results in a decreased triglyceride content in cell culture medium. Protein and gene expression analysis of mature ABCC6-deficient adipocytes showed diminished intra- and extra-cellular lipolysis, release of lipids, and fatty acid neogenesis. Therefore, our results demonstrate impaired lipid trafficking in adipocytes due to ABCC6 deficiency, highlighting adipose tissue and peripheral lipid metabolism as a relevant target for uncovering systemic PXE pathogenesis.

Pseudoxanthoma elasticum: Die Lotsenfunktion des Dermatologen

Charakteristische Hautveränderungen führen zu der Diagnose eines Pseudoxanthoma elasticum (PXE). Das PXE repräsentiert eine ektope Mineralisationsstörung, welche primär die Haut, die Augen und das arterielle Gefäßsystem betrifft. Eine frühzeitige Diagnosestellung ist entscheidend für die rechtzeitige Behandlung von extrakutanen Komplikationen. Wir verdeutlichen die Lotsenfunktion der Dermatologen und Dermatologinnen anhand einer Serie von vier unabhängigen Fällen eines PXE mit pathognomonischen Hautveränderungen und einem weiten Spektrum an systemischen Komplikationen.