Right upper arm has a small lump not painful . been there approx 6 months . what is it likley to be?

Lipoma or fibroma: If is firm it is likely to be a fibroma and if soft a lipoma. Both of these are benign. If,however, it begins to grow or becomes tender you should ask your primary care provider to look at it. Hope this helps.

Possible Lipoma: Lipomas are benign fatty tumors. They tend to feel firm or rubbery, are mobile, and are always non-tender. They do not tend to resolve on their own. They do not require treatment unless they are causing discomfort.. Seek medical attention if lump increases in size or becomes painful.