What is a strawberry patch on your skin and what is the reason for it?

Just a birthmark: Strawberry hemangiomas (also called strawberry mark or capillary hemangioma) may appear anywhere on the body, but are most common on the face, scalp, back, or chest. They are made up of small, closely packed blood vessels. They may be absent at birth, and start developing at several weeks. They usually grow rapidly, remain a fixed size for a while, and then shrink away in middle childhood.