Ovarian dysgerminoma

Dysgerminomas are malignant ovarian germ-cell tumors.

Dysgerminomas comprise only 1–2% of all malignant ovarian tumors.^{1, 2} They are malignant ovarian germ-cell tumors. Malignant ovarian germ-cell tumors are derived from primordial germ cells and are classified into several subgroups: dysgerminomas, endodermal sinus tumors, yolk sac tumors, immature teratomas, choriocarcinomas and embryonal carcinomas. Endodermal sinus tumors and immature teratomas are the most common. According to a survey performed in the USA and comprising 1262 cases of malignant ovarian germ-cell tumors registered from 1973 to 2002, the age-adjusted incidence rate of ovarian dysgerminoma per 100.000 women-years was 0.109.³ Malignant germ-cell tumors of the ovary occur in young women, 75% being diagnosed in the second and third decades of life.⁴

Ovarian dysgerminomas are characteristically solid and well-encapsulated with an average diameter of 15 cm.⁵ In section, they appear to consist of different lobules, are soft and fleshy, and gray–white or light tan. Areas of coagulative necrosis and hemorrhage typically associated with cystic change may be seen. Dysgerminomas may be bilateral: in 10% of cases, gross involvement of the contralateral ovary is present, and in another 10%, microscopic foci of tumor are found in the contralateral ovary.⁵

The most characteristic ultrasound features of ovarian dysgerminoma (in more than 90% of cases) was a purely solid tumor^6-8 divided into different lobules, with irregular internal echogenicity, with smooth lobulated contours and well defined borders, and richly vascularized at color/power Doppler examination (moderate in the 43% of cases and abundant in the 50% of cases). The lobe-like ultrasound pattern of dysgerminomas might be explained by fine connective tissue containing lymphocytes separating nodules of tumor cells as described in textbooks of pathology.⁵ Only in very few cases a moderately vascularized multilocular solid tumor has been reported.

Half of the patients analyzed in IOTA series described by Guerriero et al. had fluid in the pouch of Douglas (a common and unspecific ultrasound finding in women of fertile age) and one had ascites.⁸

At 3D power Doppler ultrasound evaluations these tumors revealed densely packed vessels, irregular branching, caliber changes and tortuosity of tumor vessels.⁸

In conclusion the ultrasound finding of a large, solid, lobulated adnexal mass with irregular internal echogenicity and highly vascularized at color or power Doppler ultrasound in a woman 20–30 years old should raise the suspicion of ovarian dysgerminoma. Analysis of hCG, AFP or LDH might be helpful for making a correct diagnosis before surgery.² The concomitant presence of a positive pregnancy test should increase the suspicion of ovarian dysgerminoma. However, in the study of Guerriero et al⁸, the larger series present in the literature, a preoperative diagnosis of ovarian dysgerminoma was not suggested in any case, but a preoperative diagnosis of ‘rare malignant tumor’ was made by the original ultrasound examiner in 59% (13/22) of the tumors.

Ovarian dysgerminomas may be detected incidentally in women with no gynecological symptoms. The most common symptoms are abdominal enlargement and the presence of a pelvic or abdominal mass felt by the patient herself, sometimes associated with pain. Torsion may cause severe pain. Occasionally, menstrual and endocrine abnormalities may be the presenting symptom. The duration of symptoms is usually short, despite the tumor being large, indicating rapid tumor growth. Dysgerminoma is the most common malignant ovarian germ-cell tumor diagnosed in pregnancy, and may also be discovered in patients investigated for primary amenorrhea, in which case it may be associated with gonadal dysgenesis and gonadoblastoma.

Ovarian dysgerminoma may produce human chorionic gonadotropin (hCG) simulating a pregnancy, and patients with ovarian dysgerminoma may have elevated serum levels of lactate dehydrogenase (LDH). Serum levels of CA 125 and placental-like alkaline phosphatase (PLAP) have been found to be elevated in some cases, but CA 125 levels are often not increased in patients with ovarian dysgerminoma. Mixed germ-cell tumors may produce alpha-fetoprotein (AFP) depending on the type and quantity of yolk sac tumor elements in the tumor.

Ovarian dysgerminomas have a good prognosis.⁹ Gordon et al.¹⁰ reported that 72 patients treated by unilateral adnexectomy for Stage IA pure ovarian dysgerminoma had a 95% 5-year survival. The recurrence rate was 17%. Recurrences usually occur within 2 years of diagnosis and are treatable.¹¹ Thus, for patients with Stage IA pure ovarian dysgerminoma who wish to preserve fertility, conservative surgery (unilateral salpingo-oophorectomy and careful staging) with close follow-up is the treatment of choice. Biopsy of the contralateral ovary might be considered in patients with dysgerminoma because occult or microscopic tumor involvement occurs in 10–15% of patients.² A diagnosis of ovarian dysgerminoma is rarely suspected before surgery. For example, in a series of 129 patients with ovarian dysgerminoma treated between 1983 and 1992, only 29 patients (22%) underwent primary surgery in a specialized gynecological oncology center.¹²

1 Zaloudek C. The ovary. In Pathology in Gynecology and Obstetrics, Gompel C, Silverberg SG (eds). JB Lippincott: Philadelphia, PA, 1994; 379–397.

2 Pectasides D, Pectasides E, Kassanos D. Germ cell tumors of the ovary. Cancer Treat Rev 2008; 34: 427–441.

3Smith HO, Berwick M, Verschraegen CF, Wiggins C, Lansing L, Muller CY, Qualls CR. Incidence and survival rates for female malignant germ cell tumors. Obstet Gynecol 2006; 107: 1075–1085.

4 Cotran RS, Kumar V, Robbins SL (eds). Robbins Pathologic Basis of Disease (4th edn). WB Sanders: Philadelphia, PA, 1989.

5 Prat J. Germ cell tumors. In Pathology of the Ovary, Prat J (ed.). Saunders: Philadelphia, PA, 2004; 251–282.

6 Lazebnik N, Balog A, Bennett S, Redline R, Liu J. Ovarian dysgerminoma: a challenging clinical and sonographic diagnosis. J Ultrasound Med 2009; 28: 1409–1415.

7 Kim SH, Kang SB. Ovarian dysgerminoma: color Doppler ultrasonographic findings and comparison with CT and MR imaging findings. J Ultrasound Med 1995; 14: 843–848.

8 Guerriero S, Testa AC, Timmerman D, Van Holsbeke C, Ajossa S, Fischerova D, Franchi D, Leone FP, Domali E, Alcazar JL, Parodo G, Mascilini F, Virgilio B, Demidov VN, Lipatenkova J, Valentin L. Imaging of gynecological disease (6): clinical and ultrasound characteristics of ovarian dysgerminoma. Ultrasound Obstet Gynecol. 2011;37:596-602.

9 Talerman A. Germ cell tumors of the ovary. In Blaustein's Pathology of the Female Genital Tract (4th edn), Kurman R (ed.). Springer: New York, 1994; 851–859.

10 Gordon A, Lipton D, Woodruff JD. Dysgerminoma: a review of 158 cases from the Emil Novak ovarian tumor registry. Obstet Gynecol 1981; 58: 497–504.

11 Vicus D, Beiner ME, Klachook S, Le LW, Laframboise S, Mackay H. Pure dysgerminoma of the ovary 35 years on: a single institutional experience. Gynecol Oncol 2010; 117: 23–26.

12 Peccatori F, Bonazzi C, Chiari S, Landoni F, Colombo N, Mangioni C. Surgical management of malignant ovarian germ-cell tumors: 10 years' experience of 129 patients. Obstet Gynecol 1995; 86: 367–372.

This article should be cited as: Guerriero S., Ajossa S. Fischerova D., Testa A.C.: Ovarian Dysgerminoma, Visual Encyclopedia of Ultrasound in Obstetrics and Gynecology, www.isuog.org, September 2015

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