There is a hard lump behind the ear. This situation is mainly seen in the following cases: First, look at the hardness of the hard lump. If it is very hard, it may be an osteoma of the mastoid process behind the ear. Osteomas are generally benign tumors and are usually removed, ground up, or excised surgically. Second, there are other cases, such as sebaceous cysts and cortical adenomas behind the ear, which are usually not too hard and can be detected locally by palpation and are also treated surgically. Third, there are neurofibromas behind the ear, which are clinically encountered, and after surgical removal, the pathology suggests neurofibromas. Fourth, there are others, such as swollen lymph nodes behind the ear, which may or may not have painful symptoms, that is, swollen lymph nodes, which are usually treated with hot compresses and anti-infection treatment.