There are a number of
conditions which can cause lump on arms. Any trauma, infection, inflammat
ion or tumors can cause lumps on arms. Papilloma virus infections, abscesses or cellulitis
, osteoarthritis, gout, rheumat
ic fever or rheumat
oid arthritis, benign or malignant tumors including nevi, melanoma, fibroma, lymphoma, lipoma or nonmelanoma skin cancers can cause a lump to appear on your arm. I will suggest you to see a doctor and get examined.