cases with carcinoma of the endometrium. Identification of multifocal disease is important because patients with disease metastatic from the uterus to the ovaries have a 30% to 40% 5-year survival, whereas those with synchronous multifocal disease have a 75% to 80% 5-year survival (20). When the histologic appearance of endometrial and ovarian tumors is different, the two tumors most likely represent two separate primary lesions. When they appear similar, the endometrial tumor can be considered a separate primary tumor if it is well differentiated and only superficially invasive.
Several basic histologic patterns are present in the clear cell adenocarcinoma (i.e., tubulocystic, papillary, reticular, and solid). The tumors are made up of clear and hobnail cells that project their nuclei into the apical cytoplasm. The clear cells have abundant clear or vacuolated cytoplasm, hyperchromatic irregular nuclei, and nucleoli of various sizes (Fig. 37.7). Focal areas of endometriosis are common and mixed clear cell and endometrioid carcinoma may occur (20). The clear cell carcinoma seen in the ovary is histologically identical to that seen in the uterus or vagina of the young patient who has been exposed to diethylstilbestrol (DES) in utero. Nuclei of clear cell carcinoma range from grade 1 to grade 3, but pure grade 1 tumors are extremely rare. Almost invariably high-grade (grade 3) nuclei are identified. Hence, clear cell carcinoma is not graded.
Borderline Brenner Tumors In the past, proliferative Brenner tumors were subclassified as proliferating tumors (those tumors that resemble low-grade papillary urothelial carcinoma of the urinary bladder) and borderline tumors (those tumors that resemble high-grade papillary urothelial carcinoma), but both groups of tumors are now classified as borderline Brenner tumors (21). Complete surgical removal usually results in cure.
Malignant Brenner Tumors These rare tumors are defined as benign or borderline Brenner tumors coexisting with invasive transitional cell carcinoma.
Figure 37.7 Clear cell carcinoma of the ovary. Note the solid variant of clear cell carcinoma with sheets of cells that have clear cytoplasm (“hobnail” cells).
The designation transitional cell carcinoma refers to a primary ovarian carcinoma resembling transitional cell carcinoma of the urinary bladder without a recognizable Brenner tumor. It is reported that those ovarian carcinomas that contain more than 50% of transitional cell carcinoma are more sensitive to chemotherapy and have a more favorable prognosis than other poorly differentiated ovarian carcinomas of comparable stage (22,23). Transitional cell tumors differ from malignant Brenner tumors in that they are more frequently diagnosed in an advanced stage and are associated with a poorer survival rate (24).
Peritoneal Carcinomas Peritoneal tumors are histologically indistinguishable from ovarian serous tumors. In the case of borderline serous peritoneal tumors and serous peritoneal carcinomas, the ovaries are normal or minimally involved, and the tumors affect predominantly the uterosacral ligaments, pelvic peritoneum, or omentum. The overall prognosis for borderline serous peritoneal tumors is excellent and comparable to that of ovarian borderline serous tumors (25–27). In the review of 38 cases of peritoneal borderline serous tumors from the literature, 32 women had no persistent disease, 4 were well after resection of recurrence, 1 developed an invasive serous carcinoma, and 1 died from the effects of the tumor (25).