<s>[INST] I have a working out related question. I was doing curls with weights and felt a slight pop on my arm (not the bone) I ignored it thinking it was my joint that popped. But when I looked at my arm it had a lump the size of a penny sticking out and a bit brighter then my skin color. Could this possibly be my vein that expanded? I have since put pressure on my arm and the lump has gone away slightly but my arm feels different not in pain but just different. I also immediately stopped working out when I noticed the lump. [/INST] Hi.noted history of lump on the arm. It could be a fibrous (fibrous tissue formation), lipoma (fatty deposit) or a cystic formation. It is best if you consult with a doctor, preferably a general surgeon, for physical examination and clinical evaluation. Other diagnostics and management will be directed accordingly. If it is any of the benign lesions mentioned above, definitive treatment is surgical excision and antibiotic treatment. Hope this helps. Good day!!~ Chat Doctor.  </s>