What is this mystery spot ? Should I be concerned ? Someone said they had a cyst that looked like…

It could just be where the ultrasound thing was moving on your stomach. Do you have any symptoms of cysts? If you're concerned I'd phone your midwife/health care provider and ask for some advice :)

I had something like that and they called it placental lakes and I had a couple of them but everything went perfectly fine through the whole pregnancy

It was transvaginal

They would tell you if you had a cyst .. you can see mine clearly in my ultrasound it's huge bigger then the poor baby! But any concerns you have you should ask your doctor.

Hmm, we'll the doctor said everything looked perfect so I guess it's not a big enough deal for him to mention. I just worry sometimes . I have another appointment set for 12 weeks and maybe it will go away by then.