Calcific uraemic arteriolopathy: a rare disease with a potentially high impact on chronic kidney disease-mineral and bone disorder.

Calciphylaxis [calcific uraemic arteriolopathy (CUA)] is a rare disease at the interface of nephrology, dermatology and cardiology. CUA most often occurs in adult dialysis patients. It is only rarely seen in patients without relevant chronic kidney disease, and only anecdotal reports about childhood calciphylaxis have been published. Clinically, CUA is characterized by a typical cascade, starting with severe pain in initially often inconspicuous skin areas, followed by progressive cutaneous lesions that may develop into deep tissue ulcerations. The typical picture is a mixture of large retiform ulceration with thick eschar surrounded by violaceous, indurated, tender plaques. The histopathological picture reveals arteriolar, often circumferential, calcification and extensive matrix remodelling of the subcutis. These findings explain the macroscopic correlation between skin induration and ulceration. The prognosis in CUA patients is limited due to underlying comorbidities such as uraemic cardiovascular disease and infectious complications. The etiology of CUA is multifactorial, and imbalances between pro- and anti-calcification factors, especially in the setting of end-stage renal disease play an outstanding role. Oral anticoagulant treatment with vitamin K antagonists is a predominant CUA trigger factor. It is speculative as to why children and adolescents only develop calciphylaxis in exceptional cases, although a seldom usage of vitamin K antagonists and the preserved mineral buffering capacity of the growing skeleton may be protective.