Degos disease

Degos disease is a very rare disorder of the small and medium sized blood vessels. The lining of these vessels breaks down resulting in occlusion that leads to necrosis.
The cause of the disease is poorly understood, but it appears to be similar to an autoimmune disorder and responds to immunosuppressants. Anticoagulants also help prevent damage.  However, most patients diagnosed with the disorder die of its complications within three years.
Degos disease at Wikipedia