Calciphylaxis in uraemic and nonuraemic settings: clinical risk factors and histopathological findings.

Background: Calciphylaxis is a life-threatening cutaneous ulcerative/necrotic disease characterized by vascular calcification/occlusion. It occurs most commonly in end-stage kidney disease (ESKD), known as uraemic calciphylaxis (UC) but can also occur in patients with chronic kidney disease (CKD) and normal kidney function (nonuraemic calciphylaxis; NUC). There are few large series of NUC in the literature.
Aim: To compare the clinicopathological features of UC and NUC.
Methods: We retrospectively compared the clinicopathological features of 35 patients with NUC during the period 2010-2020 with those of 53 patients with UC (control group). Cases were classified as NUC in the absence of all of the following: ESKD, significant CKD (defined as serum creatinine > 3 mg/dL or creatinine clearance < 15 mL/min) and acute kidney injury requiring kidney replacement therapy or kidney transplantation.
Results: NUC represented 40% of the total cases, and there was a higher number of women (P < 0.01) and a higher median body mass index (P = 0.06) compared with the control UC group. Elevated parathyroid hormone was present in 44% of patients with NUC. Most of the tested patients were positive for lupus anticoagulants (56%). NUC biopsies showed a higher rate of extravascular calcium deposits (73% vs. 47%, P = 0.03). Dermal reactive vascular proliferation was the most common dermal change (32%).
Conclusions: NUC is more common than previously reported and shows a higher predilection for obese postmenopausal women. Undiagnosed hyperparathyroidism shows a possible association with NUC. Lupus anticoagulants were positive in most patients. NUC biopsies are more likely than UC biopsies to display extravascular calcium deposition.
(© 2021 British Association of Dermatologists.)