Can Dermoid Or Haemorrhagic Cyst Cause Miscarriage?

Hi, I have been diagnosed with either a dermoid cyst or a haemorrhagic cyst (5.8cm) on my left ovary, i have also come back with a positive pregnancy, my HCG level is currently 1212 any i am 5wks pregnant going off my first day of my menstrual period, my doctor told me i could not actually be pregnant that the dermoid cyst can give wrong results, she also said my HCG levels by this stage should be higher, please tell me is it possible i may not be pregnant and if i am do any of these cysts cause any problems for pregnancy ie: miscarry?