A tendon bag on the back of the hand may be a lipoma or a tendon cyst. First of all, the performance of the two is not the same, lipoma is generally soft, the boundary is clear, pressure will not cause pain, when the finger activities, clenching the fist, finger activities, the position of the lipoma will not change significantly. If it is a tendon sheath cyst, the lump is usually hard and will move back and forth, up and down when clenching or unclenching the fingers. Lipomas can be surgically removed in general, and tendon sheath cysts also need to be surgically removed. When removing a tendon sheath cyst, the wall of the cyst must be completely peeled off to avoid recurrence.