Calciphylaxis
We all have heard about the term Myocardial Infarction which refers to the ischemic death of myocardial tissue. How will it look to have the same pathology happening in the skin of an individual ?
Calciphylaxis is derived from the word ‘calci’ meaning calcium and ‘phylaxis’ meaning protection. It was so named because upon discovery in rats, calciphylaxis appeared as if a shell made up of calcium was providing a protection to them. Later this phenomenon was found to happen in patients of renal failure and hence the same term was used for humans.
Calciphylaxis is a plaque like lesion on the skin that progresses to painful nodules.
Pathogenesis
Calciphylaxis is a condition involving vascular calcification and cutaneous necrosis. It occurs most commonly in the patients of End Stage Renal Disease.
CKD is defined as GFR <60ml/min/1.73m2 for at least three months. This decrease in GFR causes a decrease in 1,25(OH)D3 reabsorption by the Proximal tubular cells via the receptors cubulin and megalin. This leads to a decrease in net calcium absorption. This decreased levels of calcium drives the parathyroid gland to secrete more PTH to normalize the serum calcium, leading to secondary hyperparathyroidism. When the levels of calcium and phosphate increase beyond their solubility levels they tend to deposit on the walls of blood vessels causing a vascular compromise to the skin leading to necrosis.
Thus medial calcification and intimal fibrosis of the cutaneous arterioles combined with thrombotic occlusion leading to ischemic skin necrosis is found in calciphylaxis.