Thanks for coming to HCM. Can you please check with the official report and confirm if it says "lymphoma" or "lipoma". Getting a report on phone can sometimes cause confusion; if in doubt it is better to request for the spelling of the finding, but in every case, best is to get official report signed by the radiologist
Since you mentioned that you were asked to observe with information of 'fatty lump' and no immediate treatment , it is possibly lipoma or some non-cancer tumor
(lump). It is good practice to learn to do breast self-examination
Lymphoma needs biopsy
confirmation & further treatment.
Wish you good health!