Inherited
Hemorrhagic Telangiectasia -- blood vessels are more fragile than usual leading to recurrent bleeding episodes

Ehlers-Danlos syndrome --collagen that supports blood vessels is unusually weak and elastic, making blood vessels less protected and more prone to injury

Acquired
Allergic purpura --small blood vessels are inflamed and prone to leakage, a condition thought to be an autoimmune response and may be acute or chronic