Diagnosis: Calciphylaxis

The woman had calciphylaxis, a potentially life-threatening syndrome of unknown etiology that occurs almost exclusively in patients with chronic kidney disease. Data suggest that calciphylaxis is a common end point of multiple circumstances and that small-vessel occlusion is the final insult. Vascular calcification and small-vessel occlusion are constantly found in biopsy specimens. There is no age predilection; the disease more commonly affects Caucasians and females. The most frequently associated comorbid conditions include chronic kidney disease (renal transplant recipients are also susceptible), secondary  hyperparathyroidism, obesity, hypercalcemia, hyperphosphatemia, and immunosuppressant use. Most patients have a calcium-phosphate product >60-70 mg/dL2, although calcium and phosphorus levels may be normal. Often, a hypercoagulable state is found in association with this condition as well.  

Skin lesions in calciphylaxis are variable. Early lesions range from the mottled pattern of livedo reticularis to erythematous papules, plaques, and nodules. As the disease progresses, lesions become purpuric and develop a stellate appearance with central necrosis. Deeper lesions may be more nodular and larger, resembling erythema nodosum. All areas are exquisitely tender and indurated. Ninety percent of the lesions occur on the lower extremities; proximal lesions and visceral lesions, though less common, are associated with a higher mortality. 

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The diagnosis of calciphylaxis is made by histologic examination. Incisional biopsy is the preferred sampling method to ensure ample subcutaneous tissue for study; a punch biopsy specimen may be too superficial. Calcification of small- and medium-sized arterioles, intimal hyperplasia and fibrosis, subcutaneous calcium deposits, and panniculitis with an inflammatory infiltrate are seen on microscopy.

Mortality with calciphylaxis is reportedly as high as 80%, mostly due to secondary superinfection with sepsis. Medical management is mainly supportive. Potential triggers, e.g., infusion of iron dextran and use of corticosteroids, should be discontinued if possible, the calcium-phosphate product lowered, and anticoagulation considered if it is not contraindicated. Antibiotics are necessary if infection is present. Surgical intervention includes appropriate wound debridement and possible parathyroidectomy if hyperparathyroidism is present. Parathyroidectomy appears to be the single most effective tool for this condition but is untenable in some
patients, perhaps suggesting a potential role for a new medication, cinacalcet (Sensipar). Cinacalcet lowers calcium and phosphorus concentrations in the blood by reducing parathyroid hormone levels. Despite adequate management, however, the morbidity and mortality of this condition remain high.

On testing, this patient had severe hyperparathyroidism, and she was referred for parathyroidectomy and surgical debridement. Soon after treatment, her wound slowly began to heal.