If you have a history of sprains and contusions, you should go to the orthopedic department of the hospital, and if necessary, you should take X-rays and MRI and CT to rule out fractures and other injuries. 2, if you have a history of gout, and the hard lump is accompanied by redness, swelling, pain and other typical inflammatory manifestations, you need to go to the endocrinology department for auxiliary examinations. 3.Some skin diseases may also show symptoms such as a hard lump under the skin. 4.If the patient reports a hard lump in the muscle under the skin, he/she also needs to go to the general surgery department to rule out various swellings.