It should be emphasized that up to 40% of serous borderline tumors are associated with spread beyond the ovary, but high-stage disease does not necessarily warrant a diagnosis of carcinoma. The diagnosis of a serous borderline tumor versus serous carcinoma is based on the histologic features of the primary tumor (11). Up to 10% of women with ovarian serous borderline tumors and extraovarian implants may have invasive implants, and these can behave more aggressively (13). The 5-year overall survival for women with invasive implants is about 50% if stringent criteria are applied (10,13–15). Most implants are noninvasive (10,16). In the noninvasive implants, papillary proliferations of atypical cells involve the peritoneal surface and form smooth invaginations (10). In contrast, the invasive implants resemble well-differentiated serous carcinoma and are characterized by atypical cells forming irregular glands with sharp borders. Implants are usually confined to the abdominal cavity and may be seen in the pelvis, omentum, and adjacent tissues, including lymph nodes, but spread outside the abdominal cavity is rare. Death can occur as the result of intestinal obstruction (16–19).
Borderline serous tumors may harbor foci of stromal microinvasion (18). Most patients are young and International Federation of Gynecology and Obstetrics (FIGO) stage I. Stromal microinvasion is increased about ninefold in pregnant women with serous borderline tumors.
Figure 37.1 Serous borderline tumor of the ovary. Complex papillary fronds with hierarchical branching are lined with pseudostratified columnar cells. The epithelium and the stroma are clearly separated by a basement membrane, indicating no stromal invasion.
Figure 37.2 Serous borderline tumor with micropapillary features. The papillae have a non-hierarchical branching pattern and are lined by a monomorphous population of cells.
CHAPTER 37 Ovarian, Fallopian Tube, and Peritoneal Cancer
Figure 37.3 Low-grade serous adenocarcinoma of the ovary. Clusters and papillae of malignant cells are in direct contact with fibrous stroma indicative of stromal invasion.
The presence of stromal microinvasion is associated with lymphovascular space invasion in the primary ovarian tumor (and likely represents a form of true stromal invasion), but it is not associated with an aggressive clinical course, and patients with this finding should be managed in the same way as patients without stromal microinvasion.
Serous Carcinomas In malignant serous tumors, stromal invasion is present (2). The grade of tumor is important and needs to be documented. In low-grade serous adenocarcinomas, papillary and glandular structures predominate (Fig. 37.3); high-grade neoplasms are characterized by solid sheets of cells, nuclear pleomorphism, and high mitotic activity (Fig. 37.4). Laminated, calcified psammoma bodies are found in 80% of serous carcinomas. Serous psammocarcinoma is a rare variant of serous carcinoma characterized by massive psammoma body formation and low-grade cytological features. At least 75% of the epithelial nests are associated with psammoma body formation. Patients with serous psammocarcinoma have a protracted clinical course and a relatively favorable prognosis; their clinical course more closely resembles that of high-stage, progressive serous borderline tumor than serous carcinoma.
These cystic ovarian tumors have loculi lined with mucin-secreting epithelium. The lining epithelial cells contain intracytoplasmic mucin and resemble those of endocervix, gastric pylorus, or intestine. They represent about 8% to 10% of epithelial ovarian tumors. They may reach enormous size, filling the entire abdominal cavity (2).