From MedlinePlus Genetics
Pseudoxanthoma elasticum (PXE) is a progressive disorder that is characterized by the accumulation of deposits of calcium and other minerals (mineralization) in elastic fibers. Elastic fibers are a component of connective tissue, which provides strength and flexibility to structures throughout the body.

In PXE, mineralization can affect elastic fibers in the skin, eyes, and blood vessels, and less frequently in other areas such as the digestive tract. People with PXE may have yellowish bumps called papules on their necks, underarms, and other areas of skin that touch when a joint bends (flexor areas). They may also have abnormalities in the eyes, such as a change in the pigmented cells of the retina (the light-sensitive layer of cells at the back of the eye) known as peau d'orange. Another eye abnormality known as angioid streaks occurs when tiny breaks form in the layer of tissue under the retina called Bruch's membrane. Bleeding and scarring of the retina may also occur, which can cause vision loss.

Mineralization of the blood vessels that carry blood from the heart to the rest of the body (arteries) may cause other signs and symptoms of PXE. For example, people with this condition can develop narrowing of the arteries (arteriosclerosis) or a condition called claudication that is characterized by cramping and pain during exercise due to decreased blood flow to the arms and legs. Rarely, bleeding from blood vessels in the digestive tract may also occur.  https://medlineplus.gov/genetics/condition/pseudoxanthoma-elasticum