Adnexal mass...
The 58661 describes removal of adnexal structure
An adnexal mass is a lump in tissue of the adnexa of uterus, usually in the ovary or fallopian tube. Adnexal masses can be benign or cancerous.
In premenopausal women, adnexal masses include ovarian cysts, ectopic (tubal) pregnancies, and benign (noncancerous) or malignant (cancerous) tumors, endometriomas, polycystic ovaries, tubo-ovarian abscess. Most common causes for adnexal masses in premenopausal women are follicular cysts and corpus luteum cysts.
The 58662 describes fulguration
Fulguration, also called electrofulguration, is a procedure to destroy tissue (such as a malignant tumor) using a high-frequency electric current applied with a needlelike electrode.
I would use the 58661 because the cyst is being removed, not using fulguration. Also, the ovarian cyst is an adnexal structure.
Thanks!