Hi welcome to Health care magic forum.
Thanks for choosing H.C.M.F.
It appears to be the lipoma
, and nothing else. what ever pathology of left upper abdomen like gastritis
, etc will never elicit to the out side. More over it is painless at the same time causing discomfert.
I advise you to consult a surgeon for diagnosis and treatment.You may have to take C.T.scan, besides other routine tests and manual examination for confermation.
Wishing for a quick confermation of the disease and cure.If you have any doubts you can approach me for follow up.