| Discussion: |
Ovarian cysts can be found in almost all prememopausal women and about 15% of postmenopausal women. The most common cysts are produced during the normal menstrual cycle and can be follicular or luteal in origin. These cysts are benign and can range in size from 1cm to 8cm. Numerous luteal or follicular cysts, or theca-lutein cysts, can cause bilateral ovarian enlargement from an increased hCG level. The hCG level can be elevated secondary to multiple gestation, trophoblastic disease, or Rh sensitization. Endometriosis of the ovary is another cause of ovarian cysts; hemorrhage inside the cyst results in the so-called chocolate cyst. Polycystic ovarian syndrome effects young women and results in multiple 0.5cm-1cm subcortical cysts imbedded in the ovaries. The disorder is associated with increased androgen levels, infertility, hirsuitism, and obesity.
Ovarian tumors can also present as a cystic pelvic mass. These tumors originate from ovarian surface epithelia, germ cells, or sex cord stroma. Epithelial ovarian tumors are categorized as serous, mucinous, endometroid, or Brenner tumor. The most common cystic ovarian neoplasms are serous tumors, 60% of which are benign, 25% are malignant, and 15% are borderline. Serous tumors usually present as large masses, up to 40cm in diameter. Mucinous tumors also present as a large multiloculated cystic mass filled with jelly-like fluid. 80% of mucinous tumors are benign, 10% borderline, and 10% malignant. These tumors may enter the peritoneal cavity and cause psedomyxoma peritonei, which can be fatal. 20% of all ovarian cancers are endometroid tumors, which have both solid and cystic components. Endometroid tumor cells closely resemble endometrium histologically. Brenner tumors are usually benign, solid rather than cystic, and resemble transitional epithelium of the urinary bladder. Germ cell tumors represent 15-20% of all ovarian cancers and include teratomas, dysgerminomas, endodermal sinus tumors, and choriocarcinomas. Benign teratomas, or dermoid cysts, are made up of mature cells originating from more than one germ cell layer. 1% of these tumors become malignant. Malignant teratomas are made up of immature embryonic cells from more than one germ cell layer. The more immature the cells of the tumor, the more likely the tumor will spread outside the ovary. Dysgeminomas are uncommon solid tumors which are the counterpart of the testicular seminoma. Endodermal sinus tumors are rare tumors consisting of multipotential embryonic cells. These tumors characteristically produce alpha-feto protein and can be aggressive. Choriocarcinomas are usually found in combination with other germ cell tumors. These tumors are associated with an elevated chorionic gonadotropin and are highly malignant. Sex cord stromal tumors consist of granulosa-theca cell tumors, Sertoli-Leydig cell tumors, and fibromas. These tumors are usually solid and can be functional. Granulosa-theca cell tumors produce large amounts of estrogen, leading to precocious puberty, endometrial hyperplasia, and increased risk of endometrial carcinoma. Sertoli-Leydig cell tumors are made up of cells which are identical to male testicular cells and can cause masculinization. Fibromas are solid tumors and are associated with hydrothorax and ascites.
When an adnexal mass is suspected, transvaginal ultrasound is the imaging modality of choice. Ultrasound findings can help to distinguish between benign and malignant tumors. A simple cyst is characteristic of a benign tumor, consisting of anechoic fluid, thin walls, and diameter less than 2-2.5 cm. Hemorrhage within the cyst suggests a benign process such as an endometrioma, since malignant tumors do not usually bleed. A mass with a hyperechoic solid area with acoustic shadowing suggests a benign teratoma. The findings which suggest a malignant process are solid components to the mass and septations within the mass thicker than 2-3mm. Size of tumor is not helpful in differentiating benign and malignant tumors. Transvaginal ultrasound with Doppler was initially thought to aid in the identification of malignant tumors by detecting lower vascular resistance within the mass. Studies have demonstrated this theory to be unreliable in determining benign or malignant status of an ovarian mass. According to Laing et al. (2001), a solid component of an ovarian mass was the most useful finding in malignancy. Other findings suggesting malignancy include: central flow, moderate to large amount of intraperitoneal fluid, and thick septations. Other than ultrasound, CT or MRI is useful for larger masses and examining the abdomen for metastasis.
Surgery is recommended for simple cysts larger than 5cm and complex cysts of any size. Simple cysts smaller than 5cm with a normal CA-125 level may be followed with serial ultrasounds. Benign cysts have an excellent prognosis; prognosis of malignant tumors vary with the type of tumor involved and time of detection.