The bone behind the ear is protruding and hard to touch, it may be normal mastoid process, or it may be pathologic factors, such as sebaceous cysts, enlarged lymph nodes, etc., which need to be judged according to the specific situation. 1. Physiological factors: there is a raised bone behind the ear, clinically known as mastoid, is a part of the temporal bone, if there is no pain and other uncomfortable symptoms, it is a normal physiological phenomenon, without special treatment; in addition, some people in the process of development of the auricle, the cartilage did not develop into a fusion of the auricle, and part of the residual cartilage can also be manifested as a hard swelling in the auricle. 2. Pathological factors: if the patient’s ear bone bulges at the same time, there is also pain and other discomfort symptoms, it is considered to be caused by certain diseases. Such as sebaceous cysts, lymph node enlargement. (1) Sebaceous cysts: When the sebaceous gland ducts under the skin behind the ear are obstructed, the contents can be retained, leading to the appearance of localized sebaceous cysts. (2) Enlarged lymph nodes: There are many lymph nodes distributed under the skin behind the ears. When these lymph nodes are infected by bacteria or fungi and cause inflammation, it can also lead to enlargement of lymph nodes, pain and other uncomfortable symptoms. When the bone behind the ear protrudes and feels hard to the touch, you can go to the hospital in time to find out the cause.