Pseudoxanthoma elasticum (PXE), also called Groenblad-Strandberg syndrome, is a genetic disease that causes mineralization of elastic fibres in some tissues. The most common problems begin in the skin and eyes, and later in blood vessels in the form of premature atherosclerosis.
Signs and symptoms
Usually, it affects the skin first, either in childhood or in early adolescence. Small, yellowish papular lesions form and usually affects the neck, axillae (armpits), groin, and flexural creases. The skin might become lax and redundant. Many individuals have “oblique mental creases” which are basically, horizontal grooves of the chin.
PXE initially affects the retina through a dimpling of the Bruch membrane (a thin membrane separating the blood vessel-rich layer from the pigmented layer of the retina), that is only visible during ophthalmologic examinations. Eventually, the mineralization of the elastic fibres in the Bruch membrane create cracks called angioid streaks that radiate out from the optic nerve. Angioid streaks themselves do not distort vision, even if they do cross into the foveal area. This symptom is present in mostly all PXE patients and is generally noticed a few years after the start of cutaneous lesions. These cracks might allow small blood vessels that were initially being held back by the Bruch’s membrane to penetrate the retina. These blood vessels seldom leak, and these retinal haemorrhages may lead to the loss of central vision. Vision loss is a significant issue in many PXE patients.
PXE may also affect the cardiovascular and gastrointestinal systems. Gastrointestinal bleeding is a rare symptom and generally involves bleeding from the stomach. In the circulatory system, cramping pain in the leg is induced by exercise. At later stages, coronary artery diseases might develop, leading to angina and myocardial infarction (heart attack) may occur. Several other rare neurological complications might include intracranial aneurysms, subarachnoid and intracerebral haemorrhages.
The diagnostic criteria for Pseudoxanthoma Elasticum are the typical skin biopsy appearance and the presence of angioid streaks in the retina. Standards were established by the consensus of clinicians and researchers at the 2010 biennial research meeting of the PXE Research Consortium and confirmed at the 2014 meeting.
There is no guaranteed treatment that directly interferes with the disease process. Cosmetic surgery to remove excess skin has been used to improve aesthetic appearance in PXE patients, but because of the non-life-threatening nature of these symptoms, should be used with caution.
One of the most critical symptoms of PXE is choroidal neovascularization that can lead to the decline of central vision. Photodynamic therapy has often been used as a treatment, but this has been replaced with endothelial growth factor (VEGF) inhibitors (such as bevacizumab, ranibizumab, and aflibercept) with efficacy similar to their use in the treatment of age-related macular degeneration.
To limit cardiovascular symptoms, modification of cardiovascular risk factors through changes in lifestyle is recommended.
Earlier, dietary restriction of calcium was implemented with no benefit. Several potential treatments are currently being tested or have just undergone testing, including magnesium, etidronate, PPi, and tissue-nonspecific alkaline phosphatase inhibitors.