Dermoid--One or Both ovaries removed?

[BessWilson]

I am 53. Have mass--believed to be a dermoid--on rt. ovary. Only way to diagnose is to remove dermoid. Should I have one or both ovaries removed? I have been counseled to remove both ovaries because with suspicious activity in one, and low ability to diagnose ovarian CA, my risk for ovarian CA may be increased and I should act prophylactically. A hysterectomy has also been recommended--rationale is preventative again. CA125 is 10; no history of ovarian/uterine CA; no fibroids or abnormal paps; brother prostate CA; maternal and paternal aunt breast CA ages 50 and 80.  I am not menopausal, am thin, have lowish bone density and would rather leave an ovary in to get some hormonal input without sudden menopause. I am adverse to hysterectomy b/c potential complications and possible effect on sexual sensations dont seem to warrant prophylaxis in normal risk situation. Am I foolish to turn down the hysterectomy and to have only one ovary removed?  I have 2 children, ages 10 and 13.  I do not want to act selfishly if there is true risk.