There was a growth in the middle of the back a few years ago, at first I didn’t feel it now it’s getting smaller to touch. It may be caused by sebaceous cyst, lipoma or fibroma. 1. Sebaceous cysts: A lump on the back may be caused by sebaceous cysts, in which the sebum secreted by the sebaceous glands on the back cannot be discharged from the follicular opening smoothly. If you don’t feel it at the beginning and now you feel it getting smaller, it may be the result of the sebaceous cyst subsiding on its own. 2. Lipoma: A few years ago, a bag grew in the middle of the back, which may also be a lipoma formed by the fat cells gathered between the skin and muscle in the back. Lipomas subside on their own, and patients may feel that they have become smaller to the touch. 3. Fibroma: a bag grew in the middle of the back a few years ago, it may be a fibroma formed by the proliferation of connective tissues in the back muscles, which will subside on its own, suggesting that the benign possibility is large, and you can continue to observe it, and if there is a rapid increase in the process of subsiding, you have to pay attention to its malignant transformation. A few years ago, a bag grew in the middle of the back, at first I didn’t feel it, now I feel it has become smaller. There may be other reasons, if infection occurs in the process of fading or it increases in size after fading, it is recommended to consult a doctor in time to deal with the infection or to clarify the nature of the mass on the back and then carry out targeted treatment and treatment.