I have fluid (i guess a cyst) in the fallopian tube 9cmx13cm. i'm 44 and in moderate discomfort often. i have a history of endometriosis. do i need surgery? can this be cancer?

Hard to say: That sounds painful! This hydrosalpinx (swollen tube), while not necessarily dangerous, will not likely resolve on its own but will need removal which will tell us if it is truly nothing to worry about. Tubal cancers are very rare however we can never be certain until the tube is out. You have a LOT of structures in your pelvis and to make sure this is indeed a tube, your gyno's help is required!