katherine
well, i don't know how much a stone weighs in pounds and kilograms...but i can tell you that my aunt had one removed at age 16 (1977) after she had an appendicitis...the appendix had leaked a little at the time of surgery. the surgeon saw the cyst on her ovary which was the size of a pea at that time. within 4 weeks, it had grown to the size of a cantaloupe, about 5 lbs was the weight. my mother also had one removed in 1980 when it started to grow. it was the size of a grapefruit and pressed on the ovarian artery, thus cutting off the blood supply and causing the ovary to necratize. both are fine and well today and did not have any problems afterwards. there was a lady in the USA in the news a number of years ago that had let a cyst grow to some rediculous weight of over 200lbs...but i don't remember where that was. hope this helps!