RECURRENCE OF ACUTE RETINOPATHY IN PSEUDOXANTHOMA ELASTICUM

PURPOSE

To report a case of recurrent acute retinopathy associated with pseudoxanthoma elasticum and to propose a reappraisal of this entity based on multimodal imaging analysis.

METHODS

Retrospective case report. High-resolution optical coherence tomography (high-res OCT), ultra-widefield imaging, and widefield swept-source OCT angiography and en face OCT were performed.

RESULTS

A man in his 40s diagnosed with pseudoxanthoma elasticum and angioid streaks presented with two distinct episodes of acute retinopathy in his right eye during a one-year follow-up period. Acute retinopathy was characterized by rapid vision loss. High-res OCT showed multifocal hyperreflective lesions splitting the retinal pigment epithelium/Bruch membrane complex and associated with focal choroidal thickening. After the first episode, OCT angiography confirmed the development of macular neovascularization at the site of a previous inflammatory lesion. During the second episode, multimodal images showed findings consistent with epiphenomenon multiple evanescent white dot syndrome (EpiMEWDS). On en face widefield OCT, acute retinopathy was characterized by multiple hyperreflective spots scattered at the posterior pole.

CONCLUSION

Recurrence of acute retinopathy can be observed in patients with pseudoxanthoma elasticum and angioid streaks. Multimodal imaging shows that some lesions of pseudoxanthoma elasticum-associated acute retinopathy closely resemble those of punctate inner choroidopathy/idiopathic multifocal choroiditis.

Pseudoxanthoma elasticum and retinitis pigmentosa in a patient with a novel mutation in the ABCC6 gene

BACKGROUND

Pseudoxanthoma elasticum (PXE) is an autosomal recessive condition caused by mutations in the ABCC6 gene. Ocular features include angioid streaks, peau d'orange fundus, and drusen. We report a novel ABCC6 mutation causing PXE in a patient with a mixed phenotype of PXE and retinitis pigmentosa (RP).

CASE

A 37-year-old female presented with decreased peripheral vision and nyctalopia. Ocular imaging revealed angioid streaks emanating from the optic nerve as well as peripheral pigmentary changes and bone spicules. Genetic testing revealed two mutations in ABCC6 in trans. No other mutation was identified.

CONCLUSION

We present a rare case with ocular findings of PXE and RP in a patient with a novel ABCC6 mutation. The patient presented both with peripheral pigmentary changes and angioid streaks. Further investigation into this novel mutation would be beneficial to determine if the mutation is involved in the RP phenotype.

Correlation of systemic involvement and presence of pathological skin calcification assessed by ex vivo nonlinear microscopy in Pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE (OMIM 264800)) is an autosomal recessive connective tissue disorder mainly caused by mutations in the ABCC6 gene. PXE results in ectopic calcification primarily in the skin, eye and blood vessels that can lead to blindness, peripheral arterial disease and stroke. Previous studies found correlation between macroscopic skin involvement and severe ophthalmological and cardiovascular complications. This study aimed to investigate correlation between skin calcification and systemic involvement in PXE. Ex vivo nonlinear microscopy (NLM) imaging was performed on formalin fixed, deparaffinized, unstained skin sections to assess the extent of skin calcification. The area affected by calcification (CA) in the dermis and density of calcification (CD) was calculated. From CA and CD, calcification score (CS) was determined. The number of affected typical and nontypical skin sites were counted. Phenodex + scores were determined. The relationship between the ophthalmological, cerebro- and cardiovascular and other systemic complications and CA, CD and CS, respectively, and skin involvement were analyzed. Regression models were built for adjustment to age and sex. We found significant correlation of CA with the number of affected typical skin sites (r = 0.48), the Phenodex + score (r = 0.435), extent of vessel involvement (V-score) (r = 0.434) and disease duration (r = 0.48). CD correlated significantly with V-score (r = 0.539). CA was significantly higher in patients with more severe eye (p = 0.04) and vascular (p = 0.005) complications. We found significantly higher CD in patients with higher V-score (p = 0.018), and with internal carotid artery hypoplasia (p = 0.045). Significant correlation was found between higher CA and the presence of macula atrophy (β = - 0.44, p = 0.032) and acneiform skin changes (β = 0.40, p = 0.047). Based on our results, the assessment of skin calcification pattern with nonlinear microscopy in PXE may be useful for clinicians to identify PXE patients who develop severe systemic complications.

Peripheral Interventions in Patients with Pseudoxanthoma Elasticum (PXE)

OBJECTIVE

Pseudoxanthoma elasticum (PXE) is an autosomal recessive metabolic disorder that may be associated with a high prevalence of peripheral artery disease (PAD) and related symptoms. However, the evidence supporting this association is weak, as only small cohort studies are available. Furthermore, limited data are available on the outcome of lower limb peripheral arterial interventions (PAI) in patients with PXE. It was the aim of this study to clarify the prevalence of PAD, and the occurrence and outcome of PAI in patients with PXE.

METHODS

This was a retrospective review of prospectively collected data from the Dutch Expertise Centre for PXE database. Clinical data of consecutive patients with a definitive diagnosis of PXE were examined. The primary endpoint was the prevalence of PAD (defined as an ankle brachial index of < 0.9). The secondary endpoint was to report an overview of PAI and target lesion revascularisations.

RESULTS

In 285 PXE patients (median age 58 years), 50.9% of patients (n = 145) met the criteria for PAD. Seventeen patients underwent a PAI, mostly for intermittent claudication, at a median age of 51 years. The incidence of PAI was 2.25 per 1 000 patient years in patients with PAD and PXE. A total of 58 interventions was recorded, of which 35 were target lesion revascularisations in nine patients. Twenty one revascularisations were performed within a year following the primary intervention, in 16 cases due to an acute occlusion.

CONCLUSION

Within a well phenotyped and large PXE cohort, the diagnosis of PAD was prevalent in one in two patients. The observed rate of peripheral interventions was low, while the re-intervention rate was unfavourable after endovascular or bypass surgical procedures, with over half of these re-interventions indicated within a year.

A Reference Range for Plasma Levels of Inorganic Pyrophosphate in Children Using the ATP Sulfurylase Method

PURPOSE

Generalized arterial calcification of infancy, pseudoxanthoma elasticum, autosomal recessive hypophosphatemic rickets type 2, and hypophosphatasia are rare inherited disorders associated with altered plasma levels of inorganic pyrophosphate (PPi). In this study, we aimed to establish a reference range for plasma PPi in the pediatric population, which would be essential to support its use as a biomarker in children with mineralization disorders.

METHODS

Plasma samples were collected from 200 children aged 1 day to 18 years who underwent blood testing for medical conditions not affecting plasma PPi levels. PPi was measured in proband plasma utilizing a validated adenosine triphosphate (ATP) sulfurylase method.

RESULTS

The analytical sensitivity of the ATP sulfurylase assay consisted of 0.15 to 10 µM PPi. Inter- and intra-assay coefficients of variability on identical samples were below 10%. The standard range of PPi in the blood plasma of children and adolescents aged 0 to 18 years was calculated as 2.36 to 4.44 µM, with a median of 3.17 µM, with no difference between male and female probands. PPi plasma levels did not differ significantly in different pediatric age groups.

MAIN CONCLUSIONS

Our results yielded no noteworthy discrepancy to the reported standard range of plasma PPi in adults (2-5 µM). We propose the described ATP sulfurylase method as a diagnostic tool to measure PPi levels in plasma as a biomarker in the pediatric population.

Clinical Characterization of Korean Patients with Pseudoxanthoma Elasticum and Angioid Streaks

This study aimed to characterize Korean patients with pseudoxanthoma elasticum (PXE) presenting with angioid streaks. Retinal phenotypes were longitudinally evaluated by multimodal ophthalmic imaging, and targeted gene panel sequencing for inherited retinal diseases was conducted. Seven subjects from unrelated families (median age, 51.2 years) were enrolled and followed for a median of 3.2 years. Four asymptomatic patients were significantly younger than three symptomatic patients with decreased visual acuity at presentation (mean age; 38.1 vs. 61.5 years, p = 0.020). The asymptomatic patients maintained good vision (20/32 or better) and had no choroidal neovascularization (CNV) over the observation period. The symptomatic patients showed additional reduction in visual acuity and bilateral CNV occurrence during the longitudinal follow-up. Pathogenic ABCC6 variants were identified in all patients, leading to a diagnosis of PXE. Heterozygous monoallelic variants were identified in four patients and compound heterozygous variants were detected in three patients. Nine ABCC6 variants were identified, including one novel variant, c.2035G>T [p.Glu679Ter]. This is the first genetic study of Korean patients with PXE.

PSEUDOXANTHOMA ELASTICUM: SUCCESSFUL LONG-TERM MANAGEMENT OF CHOROIDAL NEOVASCULARIZATION SECONDARY TO ANGIOID STREAKS WITH PRO RE NATA INTRAVITREAL BEVACIZUMAB INJECTIONS

PURPOSE

To demonstrate how a patient with recurrent episodes of choroidal neovascularization (CNV), secondary to angioid streaks, can be managed successfully with a pro re nata regime of intravitreal bevacizumab injection over an eight-year period.

METHOD

A 32-year-old white woman with pseudoxanthoma elasticum has been followed up over an eight-year period for management of recurrent episodes of CNV in both eyes. She was educated to recognize the early signs and symptoms of CNV. Physical examination including visual acuity and slit-lamp examination as well as investigations such as macula optical coherence tomography and optical coherence tomography angiography were performed. Bevacizumab injections were given to her when she was diagnosed with CNV.

RESULTS

Multiple episodes of CNV were successfully treated with pro re nata regimes of intravitreal bevacizumab injections. The patient was able to maintain excellent visual acuity of 0 logarithm of the minimum angle of resolution even after suffering recurrent episodes of CNV.

CONCLUSION

This case report supports that a pro re nata regime of intravitreal bevacizumab injection therapy can be used successfully to treat recurrent episodes of CNV in a patient with pseudoxanthoma elasticum over an eight-year period. Early diagnosis through patient education and the use of appropriate diagnostic tools such as optical coherence tomography angiography have enabled us to deliver early treatment, resulting in an excellent outcome for this patient.

Non-exudative macular neovascularization in pseudoxanthoma elasticum

PURPOSE

To characterize morphological changes in the retina and to report the frequency and natural history of non-exudative macular neovascularization (MNV) in a cohort of pseudoxanthoma elasticum (PXE).

METHODS

A single-center, retrospective study was complemented by a cross-sectional examination. Consecutive patients with a definitive genetic and/or clinical diagnosis of PXE, visiting our department between January 2019 and December 2019, and with a minimum follow-up of 6 months were recruited. Baseline data were retrieved from each patient file. Additionally, a cross-sectional examination comprising color fundus photography, spectral-domain optical coherence tomography (SD-OCT), OCT-Angiography (OCT-A), and fundus autofluorescence was performed. The presence of typical PXE-related findings, as well as related complications, was multimodally evaluated. The prevalence and natural history of non-exudative MNV were assessed. All images were graded by two independent graders.

RESULTS

Forty-eight eyes from 24 patients (mean age 59.11 ± 18.14) with a median follow-up of 53.00 months were included. Angioid streaks and peau d'orange were observed in 46/48 and 42/48 eyes, while MNV was present in 75.00% of the cohort. The prevalence of non-exudative MNV was 33.33% (6/18). In the 2 eyes that developed exudation, time to conversion was 9.50 ± 4.95 months. No significant difference in visual acuity was found between eyes with non-exudative MNV and those with no signs of MNV.

CONCLUSION

We have shown that non-exudative MNV is a frequent finding in PXE but the majority of eyes did not develop exudation during follow-up. Our results are a clear evidence of the utility of OCT-A in the management of PXE.

A study of optic nerve head drusen in 38 pseudoxanthoma elasticum (PXE) patients (64 eyes). Location of optic nerve head drusen in PXE

PURPOSE

To investigate the prevalence and location of optic nerve head drusen and their potential association with other PXE-related ophthalmic abnormalities.

MATERIALS AND METHODS

Thirty-eight of the 155 patients (57 male and 98 female aged 49±17 years) included in this retrospective study had optic nerve head drusen. All of the patients underwent a comprehensive ophthalmic examination, including color images using red-free, blue and red filters, autofluorescence imaging and late-phase ICG frames. Comparative analysis of both groups (optic nerve head drusen or not) was conducted using R statistical software.

RESULTS

The prevalence of optic nerve head drusen in our cohort was 24.5%. In this study, no evidence of a significant link between optic nerve head drusen and other fundus abnormalities was detected. They were more commonly located in the nasal sector than in the temporal sector of the optic disc (P<0.001). They were more frequently situated superonasally than inferonasally (P<0.004), superotemporally (P<0.001) or inferotemporally (P<0.03). No central visual field defect was observed in OND+ patients who were unaffected by macular disorders.

DISCUSSION

We hypothesized this predominantly nasal primary location may result from greater sensitivity in the nasal optic nerve fibers which follow a much more angular path once they arrive in the scleral canal, accounting for accumulation of axoplasmic debris.

CONCLUSION

In PXE, optic nerve head drusen are mostly located in the superonasal quadrant, causing progressive optic nerve invasion but probably no central visual field defects.

Peripheral Linear Streaks in Pseudoxanthoma Elasticum

The authors report a case of unilateral curvilinear streaks occurring in a patient with pseudoxanthoma elasticum. These represent a previously unreported finding in this disease, as usually found in inflammatory or infective conditions. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e292-e295.].

Subretinal fibrosis is associated with fundus pulverulentus in pseudoxanthoma elasticum

BACKGROUND

Pseudoxanthoma elasticum (PXE) is a rare autosomal recessive disorder caused by mutations in the ABCC6 gene, resulting in various retinal lesions, among other systemic manifestations. Visual loss may occur in PXE, most commonly caused by choroidal neovascularization and macular atrophy, but little is known about the consequences of fundus pulverulentus (FP) in PXE. The aim of this study was to evaluate ophthalmic outcomes in patients with FP associated with PXE in a large series of PXE patients.

METHODS

In a retrospective observational study, ophthalmic outcomes were compared between two groups of age-matched patients with genetically and pathologically confirmed PXE: one group with FP versus one without FP. All included patients underwent thorough clinical examination. Further investigation (optical coherence tomography (OCT), Cirrhus, Zeiss Germany, and/or fluorescein/indocyanin green angiography) was performed in cases of suspected choroidal neovascularization (CNV).

RESULTS

The study included 13 PXE patients with FP (group 1: 8 men and 5 women, aged 45-65 years) and 47 age-matched PXE patients without FP (group 2: 19 men and 28 women). Mean patient follow-up was 63 months (range 0-132 months). Subretinal fibrosis (SRF) was more frequently associated with FP (9/26 eyes, 34.6%), compared to absence of FP (4/94, 4.2%) (p = 0.0001). Independently of SRF, FP can evolve into deep macular atrophy and/or CNV with dramatic consequences for central vision.

CONCLUSIONS

Fundus pulverulentus may occur in PXE and is most commonly associated with subretinal fibrosis in the posterior pole and visual loss by macular atrophy even in the absence of CNV.

Familial pseudoxanthoma elasticum associated with multiple comedones

Pseudoxanthoma elasticum (PXE) is an autosomal recessive disorder characterized by atypical elastic fibers that causes connective tissue abnormalities of the skin, eyes, and heart, among other organs. The disorder is rare, with a classic presentation of yellow-orange cobblestone-like papules on flexural areas, lax skin, ocular degeneration, and moribund vasculature in multiple organs. There is wide variability in the presentation of the affected organs [1]. We present two sisters with classic cutaneous findings of PXE with the additional unusual findings of numerous open comedones on the neck. To our knowledge, this is the first report of numerous open comedones in familial PXE.

Periumbilical perforating pseudoxanthoma elasticum

A 50-year-old woman presented with a 2-year history of a yellowish plaque studded with red brown keratotic papules in the periumbilical region. Histopathological examination from the yellow plaque showed curled and granular elastic fibers in the mid and lower dermis. Histopathological examination from a keratotic papule showed pathological elastic fibers and dense chronic inflammatory cells around areas of perforation. Clinicopathological correlation established periumbilical perforating pseudoxanthoma elasticum as the final diagnosis.

[Pseudoxanthoma elasticum: A disorder with different manifestations]

BACKGROUND

Pseudoxanthoma elasticum (PXE) is a rare, autosomal recessive inheritable disorder characterized by progressive elastic fibre calcification.

CASE DESCRIPTION

Here we describe two patients with different presentations of PXE. Patient A, an 11-year-old girl, visited the dermatologist because of yellow papules (pseudoxanthomas) on the side of her neck. With the aid of a skin biopsy, the dermatologist diagnosed PXE. Some years later, patient A developed symptoms of intermittent claudication due to arterial calcifications. Supervised exercise training diminished these symptoms. Patient B, a 55-year-old man, visited the ophthalmologist due to recent onset of metamorphopsia. The ophthalmologist discovered a subretinal haemorrhage and observed changes in the retina consistent with PXE. Severe loss of vision was prevented by intraocular anti-VEGF injections. Upon further investigation, pseudoxanthomas and arterial calcifications were found.

CONCLUSION

PXE is a rare monogenetic disorder with dermatological, ocular and vascular manifestations. With these two case reports we have illustrated how the initial clinical presentation and symptomatology may vary widely.

Histology-directed and imaging mass spectrometry: An emerging technology in ectopic calcification

The present study was designed to demonstrate the potential of an optimized histology directed protein identification combined with imaging mass spectrometry technology to reveal and identify molecules associated to ectopic calcification in human tissue. As a proof of concept, mineralized and non-mineralized areas were compared within the same dermal tissue obtained from a patient affected by Pseudoxanthoma elasticum, a genetic disorder characterized by calcification only at specific sites of soft connective tissues. Data have been technically validated on a contralateral dermal tissue from the same subject and compared with those from control healthy skin. Results demonstrate that this approach 1) significantly reduces the effects generated by techniques that, disrupting tissue organization, blend data from affected and unaffected areas; 2) demonstrates that, abolishing differences due to inter-individual variability, mineralized and non-mineralized areas within the same sample have a specific protein profile and have a different distribution of molecules; and 3) avoiding the bias of focusing on already known molecules, reveals a number of proteins that have been never related to the disease nor to the calcification process, thus paving the way for the selection of new molecules to be validated as pathogenic or as potential pharmacological targets.

[Current state and prospect of pseudoxanthoma elasticum (PXE)]

Pseudoxanthoma elasticum (PXE; OMIM 264800) is a rare, recessively-inherited disorder, which is characterized by progressive calcification and fragmentation of the elastic fibers in the skin, eyes, and cardiovascular system. We have collected clinical information from more than 200 Japanese PXE patients by sending mail to -1,000 hospitals in Japan. In those data, PXE is found to be accompanied by reduced visual acuity in the -30% patients. The incidences of ischemic disorders of the brain and heart in the PXE have been proved to be significantly higher than those in over 50 Japanese as control. Genetic analysis with 70 PXE cases revealed new mutations of ABCC6 that are different from those of Caucasian cases, which showed no genotype-phenotype relationship.

β-Mannosidosis with Angiokeratoma Corporis Diffusum

Beta-mannosidosis is a lysosomal disorder which is caused by a deficiency of beta-mannosidase. This disorder was first described in goats. Twelve human cases have already been reported. We present the first case in Japan in whom the diagnosis was reached from angiokeratoma corporis diffusum. Futhermore, mental retardation, hearing loss, and renal failure were also detected. Pseudoxanthoma elasticum was also present, but whether it is a complication of beta-mannosidosis or not remains unknown. The activity level of beta-mannosidase in the patient's plasma was only 2% of the normal range, while that in the patient's mother was 40%. We suggest that beta-mannosidosis should be one of the differential diagnoses when lysosomal enzyme disorders are suspected in cases of angiokeratoma corporis diffusum.

White Fibrous Papulosis of the Neck: A Chinese Case

A 48-year-old man who presented with papules on his neck was reported. The patient had multiple, discrete, non-follicular papules on the neck that were round-to-oval, 2--3 mm in diameter and pale. They had remained entirely asymptomatic. On histologic examination, there were circumscribed areas of thickened collagen bundles in the papillary to mid-dermis. This clinical and histologic picture suggested the diagnosis of "white fibrous papulosis of the neck". As far as we are aware, this is the first report of the condition from China.

Choroidal changes associated with Bruch membrane pathology in pseudoxanthoma elasticum

PURPOSE

To investigate the impact of Bruch membrane pathology on the choroid in pseudoxanthoma elasticum (PXE).

DESIGN

Monocenter cross-sectional prospective case series.

METHODS

The study included 61 eyes of 51 patients with PXE and 54 eyes of 54 normal subjects. The diagnosis of PXE was based on skin biopsy, genetic analysis or both. Eyes with PXE were subdivided into 3 groups: eyes without choroidal neovascularization (CNV) or chorioretinal atrophy (Group 1); eyes with active or fibrotic CNV (Group 2); and eyes with chorioretinal atrophy only (Group 3). Choroidal thickness was measured using enhanced-depth imaging optical coherence tomography (EDI-OCT).

RESULTS

Compared to controls (331 μm ± 24; mean ± 95% CI), mean subfoveal choroidal thickness in eyes of patients with PXE was significantly reduced within all 3 groups (Group 1: 243 μm ± 29; Group 2: 184 μm ± 28; Group 3: 104 μm ± 28; P < 0.001). Associated structural changes included apparent loss of small choroidal vessels. The difference of PXE compared to control eyes was largest close to the optic disc and approximated the level of controls toward the periphery. Within the PXE subgroups, eyes without CNV or chorioretinal atrophy (Group 1) showed the least reduction of choroidal thickness, while it was most pronounced in Group 3.

CONCLUSIONS

The results indicate that changes of Bruch membrane can be associated with choroidal alterations, which are most pronounced in the presence of advanced disease. A role of Bruch membrane in choroidal homeostasis may reflect a possible contribution of Bruch membrane alterations to CNV and geographic atrophy development in age-related macular degeneration.

Geographic chorioretinal atrophy in pseudoxanthoma elasticum

PURPOSE

To describe a series of patients with geographic atrophy independent of choroidal neovascularization (CNV) in pseudoxanthoma elasticum and to report progression over time.

DESIGN

Retrospective observational case series.

METHODS

Records of all Vanderbilt Eye Institute patients with pseudoxanthoma elasticum and at least 1 set of color fundus photographs were reviewed (41 eyes of 21 patients). Fluorescein angiography, fundus autofluorescence, and optical coherence tomography images were reviewed, when available. In patients with geographic atrophy and at least 1 year of follow-up, atrophy was measured using fundus photographs. Main outcome measures included incidence of geographic atrophy, progression over time, and macular features associated with development or progression of geographic atrophy.

RESULTS

Eight eyes (20%) of 5 patients had geographic atrophy independent of CNV. Progression was documented in 6 eyes of 4 patients followed for at least 1 year (mean 3.5 years). Mean initial and final area was 2.9 and 9.5 mm(2), respectively, and growth rate was 1.7 mm(2) per year. Of the 6 eyes, 3 had a final visual acuity of 20/20 and the other 3 ranged from 20/150 to 20/400. All 8 eyes had pattern dystrophy, and 5 had linear pigment deposits that appeared to predict development or growth of atrophy.

CONCLUSIONS

Isolated geographic atrophy independent of CNV can develop in pseudoxanthoma elasticum, causing significant vision loss. Linear pigmented pattern dystrophy appears to predate geographic atrophy. Progression is similar to age-related macular degeneration. Recognition of this feature is important, especially if therapies to slow or reverse geographic atrophy become available.

Pseudoxanthoma elasticum confirmed by genetic analysis but not by skin biopsy: a case report and review of the literature

In patients with angioid streaks, additional investigations are useful to identify underlying systemic disease, unless age and short peripapillary streaks are indicative of senile streaks as an isolated abnormality. In middle-aged or young adults with angioid streaks and no obvious systemic disease, the possibility of a hemoglobulinopathy or pseudoxanthoma elasticum (PXE) as etiologic entities should be investigated. Hemoglobinopathies can be excluded based on blood screening and the absence of typical ocular fundus changes, such as retinal vessel tortuosity. This allows making a presumed clinical diagnosis of PXE in patients with angioid streaks, based on exclusion of a hemoglobinopathy, and on the presence of extensive angioid streaks, peau d'orange, crystalline bodies and comet tail lesions. For confirmation of PXE, the gold standard was dermatologic examination and skin biopsy, but since the last decade molecular diagnosis is available. In rare cases, PXE can be diagnosed using molecular techniques in patients with apparently normal skin and negative skin biopsies, as demonstrated in this case and another case published in 2011.

Papillary dermal elastosis

We recently came across the article "Papillary dermal elastosis" by Newlove et al published in the October 2011 edition of Dermatology Online Journal. In this paper, the authors described what they interpreted to be the second case of papillary dermal elastosis, an entity we had first identified in 2009. Upon further reading of their histopathologic and clinical description, we believe this case is more consistent with the diagnosis of pseudoxanthoma elasticum-like papillary dermal elastolysis (PXE-PDE).

Pseudoxanthoma elasticum: progress in diagnostics and research towards treatment : Summary of the 2010 PXE International Research Meeting

Pseudoxanthoma elasticum (PXE), a prototypic heritable disorder with ectopic mineralization, manifests with characteristic skin findings, ocular involvement, and cardiovascular problems. The classic forms of PXE are due to loss-of-function mutations in the ABCC6 gene, which encodes ABCC6, a putative transmembrane efflux transporter expressed primarily in the liver. While considerable progress has recently been made in understanding the molecular genetics and pathomechanisms of PXE, no effective or specific treatment is currently available for this disorder. PXE International, the premiere patient advocacy organization, organized a workshop in November 2010 to assess the current state of diagnostics and research to develop an agenda towards treatment of PXE. This overview summarizes the progress in PXE research, with emphasis on molecular therapies for this, currently intractable, disorder.

Relationship between ankle brachial index and arterial remodeling in pseudoxanthoma elasticum

OBJECTIVES

Pseudoxanthoma elasticum (PXE) is an inherited metabolic disease characterized by elastic fiber fragmentation and calcification in the cutaneous, ophthalmologic, and vascular tissues. Cardiovascular manifestations such as peripheral arterial disease (PAD) are frequent in PXE. Because of the changes in the elastic properties and medial calcification of the arterial wall in PXE, the impact of the arterial remodeling on the ankle brachial index (ABI), a well-established diagnostic method for the detection and follow-up of PAD, remains to be determined in this disease.

METHODS

This was a cross-sectional, comparative, open study, which took place at the PXE Consultation Center, University Hospital of Angers. The subjects were 53 patients (mean age, 49 ± 14 years; 35 females) with PXE clinically proven on the basis of established criteria (skin changes, angioid streaks, and skin biopsy). The ABI at rest, symptoms of intermittent claudication (IC), carotid intima-media thickness (IMT), carotid-femoral pulse wave velocity (c-f PWV), compliance (CC), and β stiffness index were measured in a single-center cohort.

RESULTS

Forty-five percent of the PXE patients had an ABI ≤0.90, but only one patient had an ABI >1.40. IC was found in 23% of the patients with an ABI ≤0.90. There were no significant differences between the patients with a low and normal ABI in terms of IMT (P = .566) or β stiffness index (P = .194), but differences were significant for c-f PWV (P = .010) and CC (P = .011). Adjusted multivariate linear regression for the Framingham-Laurier score showed that patients with a low ABI had less compliant carotid arteries (B = 0.318, P = .039).

CONCLUSIONS

PAD detected by a low ABI is very frequent in PXE, although with limited prevalence of symptomatic claudication. Unexpectedly, ABI was low in such calcifying PAD and associated with lower CC, independently of atherosclerosis risk factors. These findings demonstrate that PXE represents a unique monogenic model of PAD in which the specific arterial wall remodeling could change the diagnostic value of the ABI to detect PAD.

Pseudoxanthoma elasticum: clinical, histologic, and genetic studies--a report of two sisters

CASE 1: A 24-year-old black woman was referred to our clinic in September 1999 by the department of dermatology. She was referred to confirm the diagnosis of pseudoxanthoma elasticum (PXE). Her medical history was normal. Dermatologic examination revealed confluent papules that gave the skin a "plucked chicken" appearance on the flexural surfaces in the neck, axillae, clavicle, thigh, and periumbilical area (Figure 1). The patient stated that the changes in her skin had begun in the periumbilical region at about 5 years of age and had since been slowly progressive. Physical examination showed brownish black pigmentation on the left side of the face, left eyelid, and left sclera, which was diagnosed as Nevus of Ota (Figure 2). Her visual acuity was 20/10 in both eyes, with no afferent pupillary defect. Intraocular pressure in both eyes was normal. Slit lamp examination showed no abnormalities. Findings from fundus examination revealed angioid streaks that formed an incomplete ring around the optic disc and anteriorly radiated toward the equator of the globe, multiple calcified drusen-like structures, and "peau d'orange" changes. Skin biopsy (skin tissue from the neck) was taken and the diagnosis of PXE was confirmed. Histopathologic findings revealed calcification of the elastic fibers and abnormalities of the collagen (Figure 3). The patient was not known to have sickle cell anemia or sickle cell trait, and her blood pressure levels had never elevated. Other systemic causes of angioid streaks were excluded by findings from extensive laboratory examination. Her relatives were asked to come in for examination but lived far away. One of the patient's sisters lived in Kinshasa, Africa, however, and is presented in case 2. CASE 2: The 27-year-old sister of the previous patient was examined on April 19, 2000. At examination, she was found to have PXE. Her medical history was significant for systemic hypertension since 1998 and genital hemorrhage. She underwent an ablation of a cyst of her left ovary in 1988. Her ocular history was unremarkable. On physical examination, raised (yellow) papillary lesions, typical of pseudoxanthoma, were found on the neck, axillae, clavicle, thigh, and periumbilical regions. External and anterior segment examinations (of her eyes) were unremarkable. She was found to have a best-corrected visual acuity of 20/10 in both eyes. Intraocular pressure was normal. Funduscopy revealed bilateral angioid streaks, crystalline bodies, and "peau d'orange," but to a lesser extent than in her sister. In both cases, after informed consent, peripheral blood cells were taken and sent for extraction of DNA. Analysis was performed but could not demonstrate the known gene defects of PXE.

Gronblad Strandberg syndrome with vertibrobasilar dolichoectasia

The constellation of pseudoxanthoma elasticum, ocular involvement and vascular disturbances is termed Gronblad Strandberg syndrome. Pseudoxanthoma elasticum is a genetic disorder characterized by progressive calcification and fragmentation of elastic fibres in the skin, retina and the cardiovascular system. Typically the cutaneous lesions begin in childhood, but because of their asymptomatic nature they are not noted until adolescence. In some individuals, skin lesions do not develop until later in life. If recognized early, the occurrence of retinal and gastrointestinal hemorrhage and cardiovascular complications can be minimized.

Pseudoxanthoma elasticum-like papillary dermal elastolysis

Elastolysis refers to a loss of elastic fibers. It can affect the papillary dermis, the reticular dermis, or both. Pseudoxanthoma elasticum-like papillary dermal elastolysis (PXE-PDE) is a clinicopathological entity first described by Rongioletti and Rebora in 1992 (1). It is an acquired elastolytic disorder that mainly affects the papillary dermis. Clinically it resembles pseudoxanthoma elasticum (PXE), but it differs histologically and there is no systemic involvement, in contrast to PXE.

[Pseudoxanthoma elasticum]

During childhood two women developed yellowish xanthoma-like papules on the neck. After dermatological examination and skin biopsy, the diagnosis pseudoxanthoma elasticum (PXE) was made. PXE is a hereditary metabolic disease which has an early onset with characteristic skin lesions. Early diagnosis and follow-up is essential to prevent serious ocular or cardiovascular complications. Follow-up standards are lacking for these patients.

Late-onset focal dermal elastosis: a case report and review of the literature

Late-onset focal dermal elastosis is a condition characterized by a localized increase in healthy-appearing elastic tissue in the mid and deep reticular dermis. The condition may clinically mimic pseudoxanthoma elasticum (PXE) and linear focal elastosis. We report a case of an 87-year-old woman who presented with a markedly thickened, yellow, pruritic plaque on the posterior neck and discuss the clinical and histopathologic distinctions between late-onset focal dermal elastosis, PXE, and linear focal elastosis.

[Pseudoxanthoma elasticum beyond skin, eyes and vessels]

The main clinical manifestations of pseudoxanthoma elasticum (PXE) alter small arteries, the eyes and the skin. At the microanatomical level, the feature in common is an alteration of the elastic fibres that appear dystrophic and in part calcified. The disease is genetically transmitted as an autosomal recessive trait. The gene coding for the MRP6 protein is often mutated. Thus PXE appears as a metabolic disease conveyed by serum.

[Pseudoxanthoma elasticum: a study of 22 cases]

Pseudoxanthoma elasticum is a heritable connective-tissue disorder affecting the eye, skin, and vascular system. The aim of our study was to specify the epidemiological and clinical characteristics of this disease in a hospital series. A total of 22 patients were included during a period of 19 years. There were 15 women and 7 men. Patient's mean age was of 36,1 years. Parental inbreeding was reported in 10 cases. However, the parents were apparently healty. All patients exhibited cutaneous signs. The association between pseudoxanthoma elasticum and elastosis perforans serpiginosa was reported in two cases. The histological features were characteristic in all cases. The ophthalmologic examination realized on 13 patients revealed angioid streaks in 6 cases and a orange peel aspect in one case. Cardiac evaluation performed in 11 patients did not reveal specific PXE abnormalities. A follow-up was recommended in the majority of the cases. In conclusion, a family history of PXE was frequently reported in our study mainly among brothers and sisters. The disease was probably of autosomal recessive transmission. Cutaneous lesions were often the first signs. A list of laboratory investigations is useful to search for asymptomatic visceral localizations and specify their frequency.

Pseudoxanthoma elasticum: clinical phenotypes, molecular genetics and putative pathomechanisms

Pseudoxanthoma elasticum (PXE), a prototype of heritable multisystem disorders, is characterised by pathologic mineralisation of connective tissues, with primary clinical manifestations in the skin, eyes and the cardiovascular system. The causative gene was initially identified as ABCC6 which encodes an ABC transporter protein (ABCC6) expressed primarily in the liver and the kidneys. The critical role of ABCC6 in ectopic mineralisation has been confirmed by the development of Abcc6(-/-) knock-out mice which recapitulate the features of connective tissue mineralisation characteristic of PXE. Over 300 distinct loss-of-function mutations representative of over 1000 mutant alleles in ABCC6 have been identified by streamlined mutation detection strategies in this autosomal recessive disease. More recently, missense mutations in the GGCX gene, either in compound heterozygous state or digenic with a recurrent ABCC6 nonsense mutation (p.R1141X), have been identified in patients with PXE-like cutaneous findings and vitamin K-dependent coagulation factor deficiency. GGCX encodes a carboxylase which catalyses gamma-glutamyl carboxylation of coagulation factors as well as of matrix gla protein (MGP) which in fully carboxylated form serves as a systemic inhibitor of pathologic mineralisation. Collectively, these observations suggest the hypothesis that a consequence of loss-of-function mutations in the ABCC6 gene is the reduced vitamin K-dependent gamma-glutamyl carboxylation of MGP, with subsequent connective tissue mineralisation. Further progress in understanding the detailed pathomechanisms of PXE should provide novel strategies to counteract, and perhaps cure, this complex heritable disorder at the genome-environment interface.