Us normal except-"mild heterogeneity to the spleen with borderline splenomegaly.cannot rule out lymphomatous involvement." what does this indicate?

Funky spleen: Means that the spleen is slightly enlarged and not uniform-looking but the radiologist cannot say anything else based on that test. Could be many things including (but not exclusively) a lymphoma. Your doctor may need to do additional tests depending on the clinical picture and the reason for which he/she ordered the us to begin with. Talk to him/her about its implications. Best to you.