A nodule is any abnormal structure in the body that can be described as relatively hard and roughly spherical. They often form on bones or tendons in response to trauma or other injury. They occasionally form on the vocal cords as well.
Nodules are usually benign, but can affect the functioning of the bone, tendon or vocal cord they are attached to.
In Three Stories, the Volleyball Player had a nodule on her right leg that was the result of a cancerous adenoma.