Functional Ovarian Cysts

Many women are extremely concerned to learn that they have an ovarian cyst. It is important for the clinician to remember that ovulating women normally develop ovarian cysts 2 to 3 cm in diameter every month. These could be physiologic, such as a dominant follicle or corpus luteum, or functional. The term functional is often applied to cysts that arise from a physiologic process related to ovulation. Functional ovarian cysts are not neoplastic, but are the most common incidental ovarian masses detected on physical and/or ultrasonographic examination. These functional cysts exceed 2 cm in most cases and can be associated with both pain and (occasionally in a thin woman) a palpable mass on pelvic examination. Ultrasonography will reveal a simple cyst filled with fluid with low echodensity.

Despite the fact that these physiologic or functional cysts often resolve spontaneously over time, more than 30% of laparoscopies performed to evaluate and manage adnexal masses ultimately find a functional or simple ovarian cyst.³

In some cases, hemorrhage into a functional cyst at the time of ovulation can result in ovarian enlargement and persistent pain. Ultrasonography in these cases will reveal a characteristic complex cyst partially filled with areas of high echodensity. The sudden occurrence of symptoms near midcycle and the spontaneous resolution of the cyst over weeks to months differentiate a hemorrhagic corpus luteal cyst from endometriomas or other more ominous lesions.

Observation with serial ultrasonography is the most common management for functional ovarian cysts as well. Follow-up ultrasonography in 4 to 6 weeks usually demonstrates partial or complete resolution. Although the presence of a functional cyst larger than 2 cm might increase the risk of ovarian torsion, the relatively remote risk of this emergency does not justify more aggressive preventive management.

Surgical management is sometimes required for patients with apparently functional cysts who experience severe and prolonged pain unresponsive to medical management to exclude intermittent torsion or other pathology.

Removal of functional cysts is usually somewhat bloody and can rarely be performed without rupturing the cyst. Fortunately, rupturing a functional cyst has no known adverse effect. In some cases, the cyst wall can be completely removed by peeling this thin layer from the enclosing ovarian epithelium. In most cases, this is difficult because of the frailty of the cyst wall, and a small section can be sent for histologic examination to verify that the cyst is functional in nature.

Endometriomas

Endometriomas often pose a difficult management challenge. The most likely cause of endometriosis is retrograde menstruation, as first proposed by Sampson in 1927. Patients with this disease are believed to have some other deficiency, because retrograde flow of endometrial cells occurs in 90% of women, but most of them never develop endometriosis.⁴

Theoretically, an endometrioma forms when endometriosis implants on the ovarian surface and invaginates to create a cyst. Active endometriosis implants incorporated in the cyst wall continue to secrete blood and cellular material, which accumulate to form a chocolate cyst. Because these endometrial cells implant on the ovarian epithelium and invade into the ovarian stroma, a clear dissection plane is often difficult to find during cystectomy.

Ovarian Neoplasms

Ovarian neoplasms can be either benign or malignant and can be further classified into three groups, according to the type of cells from which they originate (Table 50-2):

Table 50-2 Types of Ovarian Neoplasms

The risk of malignancy is influenced by the cell type of origin, with approximately 90% of malignancies arising from epithelial cells. The cell type origin of ovarian tumors varies according to the woman’s age.

These three groups have some anatomic correlation. Epithelial cells cover the surface of the ovary. The remainder of the ovary is made up of stroma, which can be further divided into the cortex and medullary portions. Germ cells are contained primarily in the cortical portion of the ovary, whereas sex cord cells are contained primarily in the medullary portion. Stromal cells are contained throughout the ovary.

Several clinical risk factors have been identified that increase the risk that any ovarian mass will be a malignant neoplasm. One of the most important is age. Before age 15, many ovarian tumors are malignant.⁵ In woman between ages 20 and 45, only the minority of ovarian tumors will be malignant. The risk increases with age thereafter, such that an ovarian tumor discovered in a woman between ages 60 and 69 is 12 times more likely to be malignant than a tumor in a woman between ages 20 and 29.⁶ Other important risk factors for malignant tumors include a positive family history and nulliparity.

Serous

Serous cystadenomas and cystadenocarcinomas are common, accounting for roughly 30% of all ovarian neoplasms and 40% of ovarian malignancies. On histologic examination, serous tumors will be found to be lined with ciliated columnar cells. Approximately 60% of serous ovarian neoplasms are benign, 15% are borderline, and 25% are frankly malignant. Benign serous cystadenomas comprise 25% of all benign ovarian tumors, and 25% will be bilateral.

Malignant serous cystadenocarcinomas are the most common ovarian malignancies, accounting for almost 50% of all malignant ovarian tumors. They are the fifth most common cancer in women in the United States. These tumors usually occur in women between ages 40 and 65 and are bilateral in 65% of cases.

Borderline ovarian tumors are less common than either benign or frankly malignant tumors and are bilateral in 30% of cases.

On transvaginal ultrasonography, serous cystadenomas are often seen as large, thin-walled cystic ovarian masses with an echodensity similar to water. Internal septa and solid areas suggest malignancy. During laparoscopy, tumor wall irregularity (papillae, nodularity), fixation to surrounding tissues, and solid components all suggest malignancy. The 10-year survival rate for women with serous cystadenocarcinomas is approximately 15%.

Mucinous

Mucinous cystadenomas and cystadenocarcinomas are also very common, accounting for 20% of ovarian tumors and 10% of malignancies. They can attain a huge size, often filling the entire pelvic and abdominal cavities. Compared to serous ovarian tumors, they are more often unilateral, large, and multiloculated. These loculations contain thick gelatinous fluid. On histologic examination, mucinous tumors are lined with nonciliated columnar cells. Approximately 80% of mucinous ovarian neoplasms are benign, 10% are borderline, and 10% are frankly malignant.

Mucinous cystadenomas account for 25% of all benign ovarian neoplasms. Their peak incidence of occurrence is between ages 30 and 50, and they are bilateral in 5% of cases.

Borderline and malignant mucinous tumors tend to occur in slightly older women, with a peak incidence of occurrence between ages 40 and 70. Malignant mucinous cystadenocarcinomas make up 10% of primary malignant ovarian neoplasms and are bilateral in up to 20% of cases. The 10-year survival rate is approximately 34%.

Mucinous tumors can be associated with an uncommon malignancy called pseudomyxoma peritonei. This condition is characterized by metastatic spread of well-differentiated mucin-secreting columnar cells along the peritoneal surfaces, usually from a primary mucinous tumor of the appendix. It is believed that this condition can result from intraperitoneal spillage of the contents of a borderline or malignant mucinous ovarian tumor. However, most cystic ovarian mucinous tumors associated with pseudomyxoma peritonei will be found to be metastases from a primary appendiceal tumor.

Endometrioid carcinomas and clear-cell carcinomas make up 20% and 6% of all malignant ovarian neoplasms, respectively, and are bilateral in 40% of cases.

Teratomas

Teratomas are the most common ovarian germ cell tumors and can be either benign (mature) or malignant (immature). Mature cystic teratomas are benign tumors commonly referred to as dermoids and account for about 25% of ovarian neoplasms. They are most common during reproductive life and are often incidental findings. Although 20% of dermoids are bilateral, it is not recommended to bivalve the ovary in search of a dermoid that is not seen on preoperative ultrasound.

Mature cystic teratomas are derived from at least two of the three germ layers: ectoderm, endoderm, and mesoderm. Most frequently, their cyst walls contain skin with sebaceous glands and hair follicles and thus contain greasy, yellow sebaceous material and hair. Less commonly, these tumors include cartilage, bone, thyroid tissue, or other structures. Struma ovarii is a particular type of mature teratoma comprised of more than 80% thyroid tissue and can be associated with hyperthyroidism.

Immature teratomas are rare, making up only 4% of ovarian teratomas. Unlike the pattern seen in most ovarian tumors, immature teratomas are more frequent at a younger age, and most present before age 18. Histologically, immature teratomas are composed of partially differentiated structures that resemble fetal or embryonal cell types. Neural elements, cartilage, and epithelial tissues are common. Immature teratomas are often solid; most are unilateral, in contrast to mature cystic teratomas.

Treatment for immature teratomas consists of surgical resection of the affected ovary and postoperative chemotherapy. In younger patients, an attempt is made to preserve fertility by conserving the uterus and unaffected ovary. The 5-year survival rate is between 60% and 90%, depending on the grade and stage of the tumor.

Chemical Peritonitis

A unique management concern regarding benign cystic teratomas is that untreated intraperitoneal spill of their sebaceous contents can result in chemical peritonitis. Clinically, patients present with postoperative fever and ileus, and can develop peritoneal granulomas, adhesions, and even a perihepatic mass.^7,8

The risk of chemical peritonitis has two implications for the laparoscopic surgeon. First, if a cyst punctured during laparoscopy is found to contain sebaceous material, a cystectomy or oophorectomy should immediately be performed. Leaving behind a leaking teratoma can lead to serious consequences. Second, when a dermoid cyst is removed laparoscopically, cyst rupture (reported to occur in approximately half the cases) must be appropriately treated with copious irrigation (i.e., 2 to 5L) until no oily material can be seen floating on the fluid surface.^9–11 Subsequent peritonitis has not been reported using this approach after spillage from a mature cystic teratoma.