For the causes of back nodules, the specific reasons are as follows: First, back muscle injury, strain: due to the existence of prolonged muscle injury, chronic strain on the back, there will gradually appear muscle blood circulation disorders, restrictions, and at the same time will gradually accumulate chronic aseptic inflammation, so there will often be back stiffness, especially small local muscle contracture, so there will be the appearance of hard nodules. Second, subcutaneous fat hyperplasia of the back: often more obese people caused by local subcutaneous fat hyperplasia, thus forming a local mass. Third, lipoma. Which is the specific case can be identified by ultrasound.