Non-uraemic calciphylaxis with acral necrosis

Abstract

A 47-year-old man with diabetic nephropathy—who was not on haemodialysis—presented with a 3-month history of non-healing ulcers and painful, progressive necrosis of the distal extremities. The involvement of the individual fi ngers and toes was variable (fi gure). Angiography of the aff ected extremities showed substantial linear arterial calcifi cation. Calcium– phosphate product (calcium con centration × phosphate concentration) was elevated (6·45 mmol2/L2 [reference range <5·6 mmol2/L2]) in serum. Skin biopsy of a nonnecrotic lesion on his medial calf confi rmed calciphylaxis. Although calciphylaxis can develop from heterogeneous pathological abnormalities, it often presents in the setting of uraemia and end-stage renal disease. It can occur as a consequence of disordered calcium metab olism that triggers metastatic arteriolar calcifi cation and thrombotic vaso-occlusion. The negative work-up of the most common risk factors for non-uraemic calciphylaxis, including primary hyperparathyroidism, malignancy, liver disease, and connective tissue disease, makes calciphylaxis in this patient unusual. The patient was treated with sodium thiosulfate with alkali supplementation, which attenuated the acral ischaemia and associated pain. The calcium–phosphate product concentration subsequently returned to the normal range without requiring treatment with chelation agents. However, the lesions on his extremities developed subcutaneous liquefactive necrosis that necessitated treatment with antibiotics followed by progressive amputation. This outcome is consistent with the poor overall prognosis reported in calciphylaxis from all causes.