Pseudoxanthoma elasticum (PXE) is a rare autosomal recessive connective tissue disease that affects the skin, eyes, and the vasculature. The clinical presentation varies from one individual to another.
Pseudoxanthoma elasticum (PXE) is an autosomal recessive disease characterized by progressive calcification, mineralization, and thus fragmentation of the elastic fibers present in the skin, arterial wall, and retina . This rare disorder affects the skin, eyes, cardiovascular system, and gastrointestinal (GI) system. It is a clinically heterogeneous disease that manifests in the second or third decade .
Skin features are the earliest sign. Lesions appear as small, yellow papules that coalesce to form a papule . It may be described as a rash with "cobblestone" pattern. The skin changes occur on the lateral neck with progression to other sites such as the axillae, inguinal folds, periumbilical region, and the antecubital and popliteal fossa . Hence, loose skin develops in these locations. The inner lower lip and mucosa of the vagina and rectum may be affected as well. Generally, these lesions do not resolve spontaneously .
Ocular signs include "peau d’orange" appearance on an ophthalmologic exam . This is followed later by angioid streaks, which reflect the mineralization of Bruch's membrane. As a result, neovascularization and subretinal hemorrhage may develop, which leads to loss of visual acuity . Blindness ensues if the macula is affected.
Although rare, patients are at risk for developing life-threatening sequelae such as myocardial infarction, cerebral aneurysm, ischemic strokes and other cardiovascular complications  . Also, GI bleeding is common, as it leads to hematemesis and melena .
The clinical assessment consists of the patient's history, physical exam, and the appropriate studies. The diagnosis is achieved based on the clinical picture, histopathology, and identification of mutations in the gene responsible for this disease.
The gold standard for diagnosis is the detection of one or two ABCC6 mutations. Proposed diagnostic criteria include the presence of 1) at least one ophthalmic finding: peau d’orange and/or angioid streaks and 2) at least one skin feature: characteristic lesion (with or without cutaneous laxity) and/or a positive biopsy of the skin . It is imperative that both eye and skin manifestations are present for definitive diagnosis. If either is absent, then two pathogenic ABCC6 mutations must be identified .
Patients with GI bleeding are evaluated with a complete blood count (CBC) to screen for iron deficiency anemia as well as a fecal occult blood test (FOBT). Additionally, serum lipid levels are obtained since patients are at risk for atherosclerosis. Another component of the workup includes measurement of serum calcium and phosphate, which are usually normal but may be elevated. Also, a urinalysis should be done to test for hematuria.
Very importantly, echocardiography is performed in patients with cardiac manifestations and risk factors for cardiac disease. Also, GI endoscopy is indicated in individuals with clinical signs of bleeding while a computed tomography (CT) scan of the head is warranted for those with clinical signs suggestive of a cerebrovascular accident. Furthermore, an ankle-brachial index test is beneficial in the assessment of intermittent claudication.
A thorough ophthalmologic exam that includes fundoscopy should be performed. Moreover, biannual surveillance is recommended for patients greater than 40 years old and every 2 years for those less than 40 . Additionally, patients are encouraged to monitor their visual acuity with the use of the Amsler Grid.