Microscopically, the characteristic feature is the endodermal sinus, or Schiller-Duval body (Fig. 37.22). The cystic space is lined with a layer of ﬂattened or irregular endothelium into which projects a glomerulus-like tuft with a central vascular core. These structures vary throughout the tumor, and the reticular, myxoid elements simulate undifferentiated mesoblast. The lining of the papillary infolding and the cavity is irregular, with an occasional cell containing clear, glassy cytoplasm, simulating the hobnail appearance of the epithelium in clear cell tumors. The association of EST with dysgerminoma must be emphasized if diagnosis and therapy are to be optimal (2,3).
Most EST lesions secrete AFP and, rarely, they may elaborate detectable alpha-1 antitrypsin (AAT). AFP can be demonstrated in the tumor by means of the immunoperoxidase technique. There is a good correlation between the extent of disease and the level of AFP, although discordance is observed. The serum level of these markers, particularly AFP, is useful in monitoring the patient’s response to treatment (405–409).
Figure 37.22 Endodermal sinus tumor of the ovary. Note the classic Schiller-Duval body with its central vessel and mantle of endoderm.
Rare Germ Cell Tumors of the Ovary
Surgery The treatment of the EST consists of surgical exploration, unilateral salpingooophorectomy, and a frozen section for diagnosis. The addition of a hysterectomy and contralateral salpingo-oophorectomy does not alter outcome (407). Any gross metastases should be removed, if possible, but thorough surgical staging is not indicated because all patients need chemotherapy. At surgery, the tumors tend to be solid and large, ranging in size from 7 to 28 cm (median, 15 cm) in the GOG series (397). Bilaterality does not occur, and the other ovary is involved with metastatic disease only when there are other metastases in the peritoneal cavity. Most patients have early-stage disease: 71%, stage I; 6%, stage II; and 23%, stage III (409).
Chemotherapy All patients with ESTs are treated with either adjuvant or therapeutic chemotherapy. Before the routine use of combination chemotherapy for this disease, the 2year survival rate was only about 25%. After the introduction of the VAC regimen, this rate improved to 60% to 70%, indicating the chemosensitivity of most of these tumors (392,393). With conservative surgery and adjuvant chemotherapy, fertility can be preserved as with other germ cell tumors.
Cisplatin-containing combination chemotherapy with three to four cycles of BEP should be used as primary chemotherapy for EST. The GOG protocols used three to four treatment cycles given every 3 weeks (397,410).
Embryonal carcinoma of the ovary is an extremely rare tumor that is distinguished from a choriocarcinoma of the ovary by the absence of syncytiotrophoblastic and cytotrophoblastic cells. The patients are very young; ages ranged between 4 and 28 years (median, 14 years) in two series (411). Older patients were reported (412). Embryonal carcinomas may secrete estrogen, with the patient exhibiting symptoms and signs of precocious pseudopuberty or irregular bleeding (2). The clinical picture is otherwise similar to that of the EST. The primary lesions tend to be large, and about two-thirds are confined to one ovary at the time of diagnosis. These lesions frequently secrete AFP and hCG, which are useful for following the response to subsequent therapy (408). The treatment of embryonal carcinomas is the same as for the EST (i.e., a unilateral oophorectomy followed by combination chemotherapy with BEP) (360,397).
Choriocarcinoma of the Ovary