What is a hematoma?

A hematoma is a localized collection of blood outside of blood vessels, usually caused by a break in the wall of a blood vessel due to injury. This results in the accumulation of blood in the surrounding tissues, leading to a swelling that can be felt and often turns the skin a shade of purple or blue. The term "hematoma" derives from "hemat-" meaning blood and "-oma," which often refers to a tumor or swelling.

While it's not a tumor in the traditional sense, the presence of pooled blood does create a mass effect that is why it is termed as a "blood tumor." Understanding hematomas is crucial in forensic and medical contexts, as they can provide insight into trauma and the circumstances surrounding an injury or death.