The main diseases predicted by right upper arm nodule are fibroma, sebaceous cyst, lipoma and so on. 1. Fibroma: right upper arm nodules may belong to fibroma, most of them are benign tumors, which should not be excessively squeezed or stimulated, if the nodules persistently increase in size or pain, you need to consult a doctor in time. 2. Sebaceous cysts: Nodules on the right upper arm may also be caused by sebaceous gland blockage, resulting in cysts. Asymptomatic sebaceous cysts do not require special treatment, but if there is hyperplasia, they need to be removed in time. 3. Lipoma: Lipoma can be a soft, semi-circular lump, which can cause nodules on the right upper arm, usually found in joints that affect movement. There are many causes of nodules on the right upper arm, after the symptoms appear, it is recommended to go to the hospital in time to clarify the nature of nodules, and take standardized treatment according to the doctor’s instructions.