TUMORS OF MÜLLERIAN EPITHELIUM

Most primary neoplasms in the ovary fall within this category. There are three major types of such tumors: serous, endometrioid and mucinous tumors.[98] These neoplasms range in size

and composition. Tumors may be small and grossly imperceptible or massive, filling the pelvis and even the abdominal cavity. Components of the tumors may include cystic areas

(cystadenomas), cystic and fibrous areas (cystadenofibromas), and predominantly fibrous areas (adenofibromas). On gross examination, the risk of malignancy increases as a function of

the amount of discernible solid epithelial growth, including papillary projections of soft tumor, thickened tumor lining the cyst spaces, or solid necrotic friable tissue depicting necrosis.

The most widely accepted theory for the derivation of müllerian epithelial tumors is through the transformation of coelomic mesothelium. This view is based on the embryologic pathway

by which the müllerian ducts are formed and evolve into serous (tubal), endometrioid (endometrium), and mucinous (cervix) epithelia present in the normal female genital tract (see the

section on anatomy). Such tumors occur predominantly in the ovary because coelomic epithelium is incorporated into the ovarian cortex to form mesothelial inclusion cysts. This

incorporation occurs by the formation of surface adhesions, atrophy with epithelial infolding, and

repair of ovulation sites. The close association of ovarian carcinomas with either the ovarian surface mesothelium or inclusion cysts may explain the development of extraovarian

carcinomas of similar histology from similar coelomic epithelial rests (so-called endosalpingiosis) in the mesentery.[98] However, this is clearly an oversimplification of the pathogenesis of

ovarian cancer. For example, endometrioid carcinomas may be derived from transplanted endometriosis, and some ovarian serous and mucinous (müllerian mucinous) tumors arise in

association with endometriosis.[98] The origin of most mucinous tumors is unclear. Some arise within endometriosis; other proposed origins include teratomatous epithelium.

An intriguing question is the origin of the cortical müllerian inclusion cyst (CIC) and its relationship to serous carcinomas ( Fig. 22-38 ). The continuity of pelvic mesothelium with these

müllerian cysts suggests that the former gives rise to the latter. However, similarities between some of these cysts and endometrial or tubal epithelium raise the possibility of a uterine or

tubal origin for the epithelium. Direct links between CICs and serous carcinoma are not common and studies of ovaries from women with BRCA mutations have not disclosed premalignant

changes in these cysts.[100] Regardless of their specific origin(s), ovarian epithelial tumors composed of serous, mucinous, and endometrioid cell types are emblematic of the plasticity of

müllerian epithelium and range from clearly benign, to tumors of borderline malignancy, to malignant tumors.[98]

Serous Tumors

These common cystic neoplasms are lined by tall, columnar, ciliated epithelial cells and are filled with clear serous fluid. Although the term serous appropriately describes the cyst fluid, it

has become synonymous with the tubal-like epithelium in these tumors. Together the benign, borderline, and malignant types account for about 30% of all ovarian tumors. About 75% are

benign or of borderline malignancy, and 25% are malignant. Serous cystadenocarcinomas account for approximately 40% of all cancers of the ovary and are the most common malignant

ovarian tumors. Benign and borderline tumors are most common between the ages of 20 and 50 years. Cystadenocarcinomas occur later in life on average, although somewhat earlier in

familial cases.

Figure 22-38Cortical inclusion cysts of the ovary. These cysts appear to arise from the overlying mesothelium and are presumed to be the site of origin for many ovarian epithelial

neoplasms. Another source of ovarian epithelium neoplasia is endometriosis (see Figure 22-29 ).

Figure 22-39 A, Borderline serous cystadenoma opened to display a cyst cavity lined by delicate papillary tumor growths. B, Cystadenocarcinoma. The cyst is opened to reveal a large,

bulky tumor mass. C, Another borderline tumor growing on the ovarian surface (lower).

Figure 22-40Papillary serous cystadenoma revealing stromal papillae with a columnar epithelium.

Figure 22-41Borderline serous cystadenoma exhibiting increased architectural complexity and epithelial cell stratification.

Figure 22-42Papillary serous cystadenocarcinoma of the ovary with invasion of underlying stroma.

Figure 22-43Complex micropapillary growth defines a low grade "micropapillary" serous carcinoma.

Figure 22-44 A, A mucinous cystadenoma with its multicystic appearance and delicate septa. Note the presence of glistening mucin within the cysts. B, Columnar cell lining of mucinous

cystadenoma.

Figure 22-45 A, Pseudomyxoma peritonei viewed at laparotomy revealing massive overgrowth of a gelatinous metastatic tumor originating from the appendix. (Courtesy of Dr. Paul H.

Sugarbaker, Washington Hospital Cancer Center, Washington, DC.). B, Histology of peritoneal implants from an appendiceal tumor, showing mucin-producing epithelium and free mucin

(arrows).

Figure 22-46 A, Brenner tumor (right) associated with a benign cystic teratoma (left). B, Histologic detail of characteristic epithelial nests within the ovarian stroma. (Courtesy of Dr. M.

Nucci, Brigham and Women's Hospital, Boston, MA.)

Figure 22-47Histogenesis and interrelationships of tumors of germ cell origin.

Figure 22-48Opened mature cystic teratoma (dermoid cyst) of the ovary. Hair (bottom) and a mixture of tissues are evident.

Figure 22-49Benign cystic teratoma. Low-power view of skin (top), beneath which there is brain tissue (bottom).

Figure 22-50Immature teratoma of the ovary illustrating primitive neuroepithelium.

Figure 22-51Dysgerminoma showing polyhedral tumor cells with round nuclei and adjacent inflammation.

Date: 2016-04-22; view: 664