Yolk sac tumour of ovary, YST, endodermal sinus tumour

Clinical features

YST usually occurs in girls and young women.

Histopathology

YST may occur alone on in combination with other components in a mixed germ cell tumour.

The histological appearances vary, with glandular, reticular, solid, hepatoid, poly-vesicular, parietal and papillary patterns.

Immunohistochemistry

	Yolk sac tumour	Ovarian carcinomas
Pancytokeratin	15/151	positive
cytokeratin 7	0/16 (a few cells (1-2%) stained in four cases)1	19/19 endometrioid1, 11/11 clear cell1, positive9,10
EMA	0/15 (12 cases showed staining of less than 5% of cells)1, 0/14 (not stated whether testicular or ovarian)11, 0/3 (not stated whether testicular or ovarian)12	12/12 endometrioid1, 11/11 clear cell1
CD15	9/15 (staining was less than 25% of cells)1, 2/75	15/19 endometrioid (the extent of staining was variable)1, 11/11 (10 cases showed staining of more than 50% of cells) clear cell1, 16/17 (9 ovarian and 8 vaginal clear cell carcinomas)5
WT1	0/161	2/18 endometrioid 1, 0/11 clear cell1
CD117	0/161
alpha-fetoprotein	12/15 (staining is generally focal)1, 15/152, 6/75	0/19 endometrioid1, 0/11 clear cell1, 3/17 (9 ovarian and 8 vaginal clear cell carcinomas)5

Differential diagnosis

• Glandular pattern: endometrioid adenocarcinoma. Glandular YST usually shows other patterns as well³. Rarely, YST and endometrioid carcinoma may occur together, usually in postmenopausal women^6,7,8.

• Glandular, papillary or hepatoid: clear cell carcinoma: patients with carcinoma are usually older⁴. AFP is positive in YST , but AFP has a low sensitivity and may be positive in carcinomas. CK7 and EMA are positive in endometrioid and clear cell carcinomas but not YST. CD15 is usually strongly positive in clear cell carcinomas and variably positive in the endometrioid carcinomas but negative or weakly positive in YST.

Prognosis

Hepatoid yolk sac tumours of the ovary are highly aggressive.

References

¹Ramalingam, P., A. Malpica, et al. (2004). "The use of cytokeratin 7 and EMA in differentiating ovarian yolk sac tumors from endometrioid and clear cell carcinomas." Am J Surg Pathol 28(11): 1499-1505.

²Kurman, R. J. and H. J. Norris (1976). "Endodermal sinus tumor of the ovary: a clinical and pathologic analysis of 71 cases." Cancer 38(6): 2404-19.

³Clement, P. B., R. H. Young, et al. (1987). "Endometrioid-like variant of ovarian yolk sac tumor. A clinicopathological analysis of eight cases." Am J Surg Pathol 11(10): 767-78.

⁴Ballotta, M. R., E. Bianchini, et al. (1995). "Clear cell carcinoma simulating the "endometrioid-like variant" of yolk sac tumor." Pathologica 87(1): 87-90.

⁵Zirker, T. A., E. G. Silva, et al. (1989). "Immunohistochemical differentiation of clear-cell carcinoma of the female genital tract and endodermal sinus tumor with the use of alpha-fetoprotein and Leu-M1." Am J Clin Pathol 91(5): 511-4.

⁶Horiuchi, A., R. Osada, et al. (1998). "Ovarian yolk sac tumor with endometrioid carcinoma arising from endometriosis in a postmenopausal woman, with special reference to expression of alpha-fetoprotein, sex steroid receptors, and p53." Gynecol Oncol 70(2): 295-9.

⁷Kamoi, S., Y. Ohaki, et al. (2002). "A case of ovarian endometrioid adenocarcinoma with yolk sac tumor component in a postmenopausal woman." Apmis 110(6): 508-14.

⁸Nogales, F. F., C. Bergeron, et al. (1996). "Ovarian endometrioid tumors with yolk sac tumor component, an unusual form of ovarian neoplasm. Analysis of six cases." Am J Surg Pathol 20(9): 1056-66.

⁹Vang, R., B. P. Whitaker, et al. (2001). "Immunohistochemical analysis of clear cell carcinoma of the gynecologic tract." Int J Gynecol Pathol 20(3): 252-9.

¹⁰Chu, P., E. Wu, et al. (2000). "Cytokeratin 7 and cytokeratin 20 expression in epithelial neoplasms: a survey of 435 cases." Mod Pathol 13(9): 962-72.

¹¹Niehans, G. A., J. C. Manivel, et al. (1988). "Immunohistochemistry of germ cell and trophoblastic neoplasms." Cancer 62(6): 1113-23.

¹²Wick, M. R., P. E. Swanson, et al. (1987). "Placental-like alkaline phosphatase reactivity in human tumors: an immunohistochemical study of 520 cases." Hum Pathol 18(9): 946-54.

This page last revised 24.12.2004.