Introduction
Pseudoxanthoma Elasticum is a rare autosomal recessive multisystem disorder also known as Grönblad-Strandberg syndrome. There is pathological fragmentation and mineralization of elastic fibres in the dermis. It mainly involves the connective tissue of skin, tunica media and intima layer of blood vessel and Bruch’s membrane of retina.
The leading cause of this disorder is the lack of functional ATP binding cassette transporter gene multidrug resistance associated protein 6 [ABCC6], which has been mapped to chromosome 16p13. This further causes the deposition and accumulation of calcium with other minerals in the elastic tissue.
Case Report
A 26 years old female presented with yellow-orange asymptomatic lesions on right lateral side of neck of 1 year duration and was increasing in size. The patient had no complaints of pain or inflammatory signs on and around the lesions with no history of treatment.
Past history, family history, personal history and drug history were non-contributory.
Clinical examination
On local examination - yellow-orange micro papules coalescing to form plaques of size ranging from 1 x 1 cm2 to 1.5 x 2 cm2 in dimension, well circumscribed, smooth surface, firm in consistency, shiny lesions were noticed over right lateral side of neck. [Figure 1]
Hair, nails, mucous membranes and other systemic examinations were normal.
Fundoscopy revealed bilateral myopic degenerative changes (lattice degeneration) and peau d'orange appearance of retina with no other specific findings. [Figure 2]
Investigation
Routine haematological investigation, urine analysis, liver function tests, renal function tests, blood pressure measurement, electrocardiogram, examination of arterial stiffness and abdominal echography were done, which were within the normal limits.
Histopathology: It showed atrophic epidermis with abnormal bright pink elastic fibres in the mid-dermis. [Figure 3]
Discussion
Pseudoxanthoma elasticum is a rare inherited multisystem disorder characterized by pathological calcification of the elastic connective tissue, involving predominantly the skin, eyes (retina Bruch's membrane) and cardiovascular system. The precise prevalence of this illness is unknown; however, a variable involvement between 1:25,000-100,000 inhabitants worldwide is estimated, with slight predominance of females.1
More than 120 different mutations in ABCC6 have been identified, and PXE is now considered to be recessively inherited in most cases. ABCC6 is predominantly expressed in the liver and kidneys, suggesting that transporter dysfunction may lead to accumulation of an unknown substrate in the blood causing secondary dystrophic changes of elastic tissues. Therefore, PXE would not seem to be a primary disorder of elastic fibres, rather than a systemic metabolic disease.2
At initial stage, skin lesion manifests as flesh coloured to yellow-orange papules which progressively coalesce to form plaque; which is seen in this case. Later the affected skin becomes lax and redundant. It mainly involves the flexure area starting from sides of neck followed by armpits, cubital and popliteal region, groin and periumbilical area.3
Eye lesion manifests as orange peel retina due to calcification of Bruch’s membrane presents as dark spots at peripheral zone of retina.4, 5 Comet lesion which is pathognomonic of PXE are chorio-retinal atrophic spots. 3 Angioid streaks due to rupture and mineralization of Bruch’s membrane is the characteristic eye sign of PXE. It also involves neovascularization leading to subretinal haemorrhage and scar formation resulting in loss of vision.5
The major cause of morbidity is the CVS manifestation. It manifests as hypertension, angina pectoris to cardiac arrest and strokes at an early age. There are some gastrointestinal symptoms such as melena and hematemesis may also be present.6
Histopathology shows elastorrhexis in the middle dermis with positive Von Kossa and Verhoeff-Van Gieson stain for calcification and elastic tissue respectively.7 Deposits are mainly of hydroxyapatite and calcium biphosphate, but iron, phosphate, and carbonate with abnormal collagen fibres and proteoglycans may also be observed.8
PXE is diagnosed on the basis of clinical, histopathological and genetic analysis. It requires multi-disciplinary approach which consist of regular monitoring of cardio-vascular and ophthalmological complications.
It is an incurable disease. Although, some laser therapy, photodynamic therapy, macular translocation surgery for cosmetic satisfaction and anti-endothelial growth factor to improve and delay the loss of vision may be of some benefit.
Conclusion
Being rare in occurrence, diagnosis is further challenging in patients with earliest focal skin lesions. Due to lack of specific management regular follow-up of these patients is very vital.
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