Bone Scan for Diagnosis of Calciphylaxis?

Calciphylaxis (also called calcific uremic arteriolopathy) is a syndrome of vascular calcification, thrombosis, and necrosis, occurring almost exclusively in ESRD patients.  The diagnosis is typically achieved by clinical exam--demonstrating painful, necrotic, and sometimes ulcerating lesions usually on the lower extremities. Because there are other clinical entities which can cause similar lesions (e.g., nephrogenic sclerosing dermopathy, cryoglobulinemia, cholesterol emboli, vasculitis, etc), sometimes we need a "gold standard".  Not uncommonly, a skin biopsy is carried out for the definitive diagnosis of calciphylaxis.  

However, there is some danger in biopsy:  many of these patients have a difficult time with wound healing, and it would be preferable to have a non-invasive manner by which to support the diagnosis of calciphylaxis.  A 2002 KI article by Fine and Zacharias provides evidence that a bone scan is fairly sensitive for this diagnosis and could be used in lieu of a biopsy. Their analysis indicated that 34 out of 36 patients with a diagnosis of calciphylaxis had an abnormal bone scan--most commonly reflected as showing increased uptake in the calves, typically in the areas of pain/ulceration (as shown on the left).  Of note, this particular study does not really address how specific a bone scan is at excluding alternative causes of this type of dermopathy, but could still potentially be useful in the right clinical setting. Unfortunately, calciphylaxis still carries with it a very high mortality rate.