Calciphylaxis: An important imitator of cutaneous vasculitis

Vitamin K-Dependent Protein Activation: Normal Gamma-Glutamyl Carboxylation and Disruption in Disease

Vitamin K-dependent (VKD) proteins undergo an unusual post-translational modification, which is the conversion of specific Glu residues to carboxylated Glu (Gla). Gla generation is required for the activation of VKD proteins, and occurs in the endoplasmic reticulum during their secretion to either the cell surface or from the cell. The gamma-glutamyl carboxylase produces Gla using reduced vitamin K, which becomes oxygenated to vitamin K epoxide. Reduced vitamin K is then regenerated by a vitamin K oxidoreductase (VKORC1), and this interconversion of oxygenated and reduced vitamin K is referred to as the vitamin K cycle. Many of the VKD proteins support hemostasis, which is suppressed during therapy with warfarin that inhibits VKORC1 activity. VKD proteins also impact a broad range of physiologies beyond hemostasis, which includes regulation of calcification, apoptosis, complement, growth control, signal transduction and angiogenesis. The review covers the roles of VKD proteins, how they become activated, and how disruption of carboxylation can lead to disease. VKD proteins contain clusters of Gla residues that form a calcium-binding module important for activity, and carboxylase processivity allows the generation of multiple Glas. The review discusses how impaired carboxylase processivity results in the pseudoxanthoma elasticum-like disease.

Generalized Weakness in a Transplant Patient: A Case Presentation

Generalized weakness in transplant patients is a major complaint in tertiary rehabilitation hospitals. The diagnosis and management of generalized weakness in this population pose challenges for physicians. We present the case of a transplant patient with generalized weakness who was eventually diagnosed with calciphylaxis using a multidisciplinary diagnostic approach of electrodiagnostics, vascular study, and skin biopsy. Calciphylaxis is a rare cutaneous disorder that mimics other collagen vascular diseases in its presentation and fulminant course. Physiatrists should be cognizant of calciphylaxis, as it signals a poor prognosis if not correctly diagnosed and treated in a timely manner, with high incidence of sepsis, wound pain, and disability.

LEVEL OF EVIDENCE

V.

Successful treatment of calciphylaxis by a multidisciplinary approach

A 48-year-old woman performing peritoneal dialysis for end-stage renal disease presented with a painful leg ulcer. The investigation revealed an elevated parathyroid hormone level and the histological examination of the biopsy tissue from the ulcer revealed medial calcification of the arterioles, consistent with calciphylaxis. The patient developed additional ulcers in the lower limbs and treatment with antibiotics, cinacalcet, sevelamer, sodium thiosulfate, low calcium dialysate and hyperbaric oxygen therapy was instituted. The patient had a favourable outcome and after 9 months the ulcers had healed and the parathyroid hormone level reached the normal range. Calciphylaxis is a rare and life-threatening disorder associated with a mortality of 60-80%. Its pathogenesis is not fully understood hence there is no consensus in the treatment of this pathology.

Calciphylaxis: a report of six cases and review of literature

Calciphylaxis is usually a fatal condition that develops in a few chronic renal failure patients, and it is characterized by calcifications in subcutaneous arteries, infarcts in skin, and the neighboring subcutis. Calciphylaxis, once considered as a rare condition, has been reported to have an annual incidence of 1% and a prevalence of 4% in dialysis patients. We describe our clinical experience in six end-stage renal disease patients on dialysis that presented with calciphylaxis and died due to sepsis, and review the pathogenesis, epidemiology, clinical and histopathologic features, and treatment of calciphylaxis. Physicians should initially consider the possibility of calciphylaxis in case of development of skin lesions in chronic renal failure patients with impaired calcium, phosphorus, and parathyroid hormone levels. The most important cause of mortality in this condition is infection. Therefore, differential diagnosis of these lesions from systemic vasculitis in their early stages and withdrawal of immunosuppressive therapy that increases the tendency to infections are essential.

Calciphylaxis cutis: a case report and review of literature

Calciphylaxis is a poorly understood syndrome of vascular calcification and skin necrosis. It affects 1-4% of the population with end stage renal disease (ESRD). Disorders implicated in the pathogenesis of calciphylaxis include chronic renal failure, hypercalcemia, hyperphosphatemia, an elevated calcium-phosphate product, and secondary hyperparathyroidism (Essary, L.R. and Wick, M.R. (2000) Cutaneous calciphylaxis. An underrecognized clinicopathologic entity. Am. J. Clin. Pathol. 113, 280-287, Beitz, J.M. (2004) Calciphylaxis:an uncommon but potentially deadly form of skin necrosis. Am. J. Nurs. 104, 36-37.). Although these abnormalities are extremely common in-patients with ESRD, calciphylaxis is relatively rare. The mortality rate of calciphylaxis is about 60-80%. The leading cause of death is sepsis from necrotic skin lesions (Hitti,W.A., Papadimitriou, J.C., Bartlett, S. and Wali, R.K. (2007) Spontaneous cutaneous ulcers in a patient with a moderate degree of chronic kidney disease: a different spectrum of calciphylaxis. Scand. J. Urol. Nephrol.1-3.). Here, we report a case of calciphylaxis in a 23-year-old female with past history of chronic renal failure, renal transplantation and intake of immunosuppressive drug. The relevant literature was discussed.

Recognizing calcific uremic arteriolopathy in autoimmune disease: an emerging mimicker of vasculitis

Calcinosis has long been associated with autoimmune disease and has a distinctive profile in scleroderma, dermatomyositis, systemic lupus erythematosus, and overlap syndromes. However, there have also been a number of case studies of calcific uremic arteriolopathy, or calciphylaxis, described within vessels, including patients with chronic renal insufficiency and several forms of vasculitis. Interestingly, the calciphylaxis associated with vasculitis appears to be unique, although relatively uncommon and is likely secondary to a disruption in the calcium-phosphate-parathyroid hormone axis. However, there appears to be an additional trigger, given that calciphylaxis is seen both in the absence of chronic kidney disease, and in the absence of a deranged calcium-phosphate-parathyroid hormone axis. These additional triggers include a high female predominance, obesity, diabetes and, possibly, warfarin use. In this review, we describe the clinical features of calciphylaxis, particularly in the context of autoimmune disease.