Well, we'll take a cyst over a solid mass any day! When I think of simple cysts vs. complex cysts, I visualize them this way. Picture a glass of orange juice. A simple cyst would be like the "no pulp" juices... You take a drink, and it goes down nice and smooth. A complex cyst would be like the varieties with pulp in them. Some have more pulp, some have less, but when you look in the glass, you see "stuff" floating around, and when you take a drink, you feel the stuff as you sip it and swallow. With orange juice, we know what the "stuff" is... or at least we hope we do! With complex cysts, the "debris" could be lots of different things... very rarely, some of that "stuff" could be a stray cancer cell. It might be like finding a seed in your orange juice, instead of just pulp. So that is why they follow up in six months.
This, of course is an extremely simplified analogy. But this is the typical route that most doctors follow with complex cysts. It really is probably nothing. But if they see changes in 6 months, then they probably would want to aspirate or biopsy. 6 months, in terms of breast cancer, is a very short time. It is a slow-growing cancer, for the most part.
I've read estimates that about 5 percent of cysts are classified as "complex." Of that 5 percent, less that 1/2 of a percent are turn out to have malignant cells.
Are you having your screenings done at a breast center? If you are, talk to your doctor about ordering a "diagnostic" mammogram instead of a "screening" next time. They usually schedule diagnostics on a day when the radiologist is on site, and then he/she reads your mammogram while you wait. If they want follow-up compression views or ultrasounds, they will typically do it right then and there, rather than having to reschedule with them for another day.
Hope this helps! And congrats on being the proud possessor of a cyst! LOL