Pyrogenic Granuloma

A benign vascular tumor of the skin or mucus membranes characterized by rapid growth and friable surface. (A friable surface is something that can tear and bleed easily)

Although the name suggests an infectious etiology, no one knows what initially causes them to form. Most theories revolve around it being a hyperplastic neovascular (new blood vessels)  response to an angiogenic stimulus with an imbalance of promoters and inhibitors.

(Hyperplastic - an increase in the amount of organ tissue resulting from proliferation) 

One of the growth factors involved is VEGF. Also, decorin (a protein from a specific gene segment and a component of connective tissue. It results from cell duplication and its primary is regulation during the synthesis stage of the cell cycle).

During the synthesis stage of the cell cycle it appears that transcription factors are opening segments when they shouldn't be, causing over production.

As new blood vessels are being formed, there's also synthesis of more skin cells. This process is happening very quickly and there's no message to stop.