I found this info online for you:
website: http://www.lef.org/protocols/prtcl-145.shtml#complex
"Complex Cysts
Complex cysts have more than one compartment within the cyst. Ultrasonography is valuable in differentiating simple cysts from complex cysts or solid masses (Bassett et al. 1991). Complex cysts are somewhat more likely to be cancerous, so doctors will often order further tests, beginning with fine needle aspiration and perhaps a biopsy, to be certain the cyst is not cancerous or pre-cancerous."
I don't want this to scare you. I have had a biopsy before for a cyst also. Mine was benign. Sometimes we scare ourselves when we shouldn't tho. As a friend from another forum says "Don't Waste A Good Panick".
Best of luck to you!
Deadra