Do i have to go back in 6 months if a cyst shows up on my mammogram?

Depends: It depends on the recommendation from the radiologist and your MD.

Maybe: If a cyst shows up on mammogram and nothing is suggested but repeat films the interpretation is benign. Using a sonogram, the cyst fluid should be defined and aspiration performed. If the fluid is then removed a repeat mammogram in 1 year is fine. If fluid cant be aspirated then a follow up should probably be performed and the cyst is found to be larger or has resolved.

Cyst: For a simple(BIRADS category 2) cyst, no follow up is necessary. There is essentially no chance of malignancy. It can be aspirated if it is painful or otherwise symptomatic. A cyst, however, cannot generally be diagnosed as a cyst on mammography. Ultrasound is necessary.