Cat Hard Lump Left Belly My Cat Has A Lump!!!!?

My cat has a lump!!!!? - cat hard lump left belly

She has a small oval worm as a hard lump at the left shoulder that bothers me, but I can give him to the vet, as my mother said do not worry if the mass of about 3-4 inches long and 1 / 2 inches wide, plz help