Acute respiratory failure due to "pulmonary calciphylaxis" in a maintenance haemodialysis patient

Calciphylaxis is a rapidly developing, fatal process of vascular calcium deposition with prominent cutaneous manifestation. We treated a long-term haemodialysis patient who developed an analogous disorder limited to the lungs. A 57-year-old man was admitted for initiation of peritoneal dialysis because limited cardiac reserve precluded further haemodialysis. He was treated successfully for pneumonia until hypoxia and progressive hypercalcaemia developed. (99m)Tc-methylene disphosphonate scintigraphy showed diffusely increased pulmonary uptake. Death supervened despite aggressive and successful treatment of hypercalcaemia. Autopsy studies included immunohistochemistry and morphometric studies of bone. Alveolar capillary walls showed diffuse calcium deposition. Both gross and microscopical findings differed from those of typical metastatic calcification in dialysis patients. Immunoreactivity for parathyroid hormone-related protein was present in the lesions. Bone histomorphometry indicated mild osteitis fibrosa. Pneumonia is believed to have caused local synthesis of parathyroid hormone-related protein that, along with high calcium x phosphorus product, contributed to calcium deposition. By analogy with the cutaneous process we termed the deposition "pulmonary calciphylaxis".