Figure 37.16 Survival of patients with epithelial ovarian cancer by substage. (From Berek JS, Hacker NF. Berek & Hacker’s Gynecologic Oncology. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2010:491, adapted with permission from Heintz APM, Odicino F, Maisonneuve P, et al. Carcinoma of the ovary. In Twenty-sixth annual report of the results of treatment of gynaecological cancer. Int J Gynecol Oncol 2006;95(suppl 1):S161–S192.
Compared with epithelial ovarian cancers, other malignant tumors of the ovary are uncommon.
Nonepithelial malignancies of the ovary account for about 10% of all ovarian cancers (2,3,342). Nonepithelial ovarian cancers include malignancies of germ cell origin, sex cord– stromal cell origin, metastatic carcinomas to the ovary, and a variety of extremely rare ovarian cancers (e.g., sarcomas). Although there are similarities in the presentation, evaluation, and management of these patients, the tumors have unique qualities that require a special approach (2,342–345).
Germ Cell Malignancies Germ cell tumors are derived from the primordial germ cells of the ovary. Their incidence is about one-tenth the incidence of malignant germ cell tumors of the testis, so most of the advances in the management of these tumors are extrapolations from experience with the corresponding testicular tumors. Although malignant germ cell tumors can arise in extragonadal sites such as the mediastinum and the retroperitoneum, most germ cell tumors arise in the gonad from undifferentiated germ cells. The variation in the site of these cancers is explained by the embryonic migration of the germ cells from the caudal part of the yolk sac to the dorsal mesentery before their incorporation into the sex cords of the developing gonads (2,3,342).
Table 37.5 Histologic Typing of Ovarian Germ Cell Tumors 1. Primitive germ cell tumors 3. Monodermal teratoma and somatic-type
A. Dysgerminoma tumors associated with dermoid cysts
B. Yolk sac tumor A. Thyroid tumor
C. Embryonal carcinoma 1. Struma ovarii
D. Polyembryoma a. Benign
E. Non-gestational choriocarcinoma b. Malignant
F. Mixed germ cell tumor B. Carcinoid 2. Biphasic or triphasic teratoma C. Neuroectodermal tumor
A. Immature teratoma D. Carcinoma
B. Mature teratoma E. Melanocytic 1.
Solid F. Sarcoma 2.
Cystic G. Sebaceous tumor a.
Dermoid cyst H. Pituitary-type tumor b.
Fetiform teratoma (homunculus) I. Others
Adapted from Tavassoll FA, Devllee P, eds. World Health Organization classification of tumours. Pathology and genetics of tumors of the breast and female organs. Lyon: IARC Press, 2003.
substances in tumors is correlated, a classification of germ cell tumors emerges (Fig. 37.17) (346).
In this scheme, embryonal carcinoma (a cancer composed of undifferentiated cells) synthesizes both hCG and AFP, and this lesion is the progenitor of several other germ cell tumors (346–348). More differentiated germ cell tumors, such as the endodermal sinus tumor, which secretes AFP, and the choriocarcinoma, which secretes hCG, are derived from the extraembryonic tissues; the immature teratomas derived from the embryonic cells have lost the ability to secrete these substances. Pure germinomas do not secrete these markers.