Ovarian germ cell tumor overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Monalisa Dmello, M.B,B.S., M.D. [2]
Overveiw
Ovarian germ cell tumor is a disease in which malignant cells form in the germ cells of the ovary. Germ cell tumors begin in the reproductive cells of the body. Ovarian germ cell tumor are rare tumors, accounting for 2% to 3% of all ovarian cancers. The median age for diagnosis is 16 to 20 (range 6 to 40 years).[1] Ovarian germ cell tumor may be classified into 7 subtypes based on histology.[2] The most common ovarian germ cell tumor is called dysgerminoma. Abnormal gonads (due to gonadal dysgenesis and androgen insensitivity syndrome) have a high risk of developing a dysgerminoma. Ovarian germ cell tumor must be differentiated from other neoplastic ovarian mass, non neoplastic ovarian mass, and adnexal mass. Symptoms of ovarian germ cell tumor include abdominal distention, acute/ sub acute abdominal pain, menstrual irregularities, and precocious puberty.[3] Physical examination of patients with ovarian germ cell tumor is usually remarkable for vaginal bleeding, abdominal distention, and adnexal mass.[3] The laboratory findings associated with ovarian germ cell tumor are the following: serum lactate dehydrogenase (LDH), human chorionic gonadotropin (HCG), CA-125, and alpha-fetoprotein (AFP). Depending on the extent of the tumor at the time of diagnosis, the prognosis may vary. CT, MRI, and ultrasound are used in combination to distinguish between the subtypes of ovarian germ cell tumors.[4][5][6] However, the prognosis is generally regarded as good.[7] The mainstay of therapy for ovarian germ cell tumor is chemotherapy and surgery.[8][9][10][11]
Classification
Ovarian germ cell tumor may be benign or malignant. Each category sub classified to different types based on histologic features.
Pathophysiology
The pathophysiology of ovarian germ cell tumors depends on the histological subtype. However, their origin is the primordial germ cells that transformed pathologically in different stages of development. It is difficult to distinguish subtypes of ovarian germ cell tumor on gross pathology alone. The majority of ovarian germ cell tumors have a solid and cystic appearance with areas of hemorrhage and necrosis. On microscopic pathology, ovarian germ cell tumors may be characterized by a uniform “fried egg” appearance (dysgerminoma), presence of Schiller-Duval bodies (yolk sac tumor), presence of embryonic-like neural, gastrointestinal, and/or cartilaginous tissue (teratoma), or mixed histopathological features (embryonal cell carcinoma).
Epidemiology and Demographics
In USA, the age-adjusted incidence of malignant ovarian germ cell tumor is 0.41 per 100,000 women. Incidence of these tumors increases from 5 years of age, although it may be present during infancy, and this increase continues to peak between the age of 15 to 19 years which is approximately 1.2 per 100,000 women. Another peak incidence of these tumors has been reported among those aged 65 years old or older where teratoma is the most common type observed. The incidence is higher among non-white ethnicity (other than black, especially Hispanic and Asians) followed by white and black individuals. Females are more commonly affected by germ cell tumors than males. These tumors also account for a greater proportion of ovarian tumors in the Asia and Africa.
Risk Factors
Gonadal dysgenesis and androgen insensitivity syndrome are known risk factors for the development of ovarian germ cell tumors. There are also other maternal factors that have been observed to be associated with increased risk of the development of these tumors in daughters. Factors such as maternal use of exogenous hormones, maternal elevated body mass index, and reproductive factors.
Differentiating From Ovarian Germ Cell Tumor Other Diseases
Ovarian germ cell tumor must be differentiated from other diseases that cause ovarian mass, such as Stein-Leventhal syndrome, ovarian teratoma, tubal pregnancy, ovarian epithelial tumors, ovarian sex-cord stromal tumors, and tubo-ovarian abscess.
Prognosis
The prognosis of germ cells of the ovary depends on the type of the tumor and its malignant potentials. Possible complications of benign teratomas are a rupture and ovarian torsion also malignant transformation. Prognosis is generally excellent in the mature teratoma, but in case of simultaneous malignant transformation, the 5-year survival rate of patients is approximately [15-30]%. The 5-year survival rate of the patient even with disseminated dysgerminoma at the time of diagnosis is above 90%. The overall 5-year survival rate for yolk sac tumor, embryonal carcinoma and choriocarcinoma are approximately 80%.
Staging
According to the FIGO and TNM cancer staging system, there are 4 stages of ovarian germ cell tumor. Surgery is the mainstay of staging for ovarian germ cell tumors.
History and Symptoms
The clinical manifestations of patients with ovarian germ cell tumors depend on the type of the tumor and its potential to produce hormonal materials. Usually, they present with abdominal pain or distention, menstrual irregularities, symptoms of virilization, rapidly growing abdominal/pelvic mass, acute abdominal pain from complications such as necrosis, capsular distention, rupture or torsion and or simply they can be asymptomatic.
Ovarian Germ Cell Tumor Physical Examination
Patients with germ cells of the ovary usually appear normal. Physical examination of these patients is usually unremarkable and the tumors tend to be discovered incidentally or during imaging workups for another reason. When symptomatic, the physical examination may be remarkable for Abdominal/pelvic mass and/or signs of virilization, precocious puberty, and pregnancy depending on the capacity of the tumor for the production of hormones.
Ovarian germ cell tumor Laboratory Findings
The laboratory findings associated with ovarian germ cell tumor are the following: serum lactate dehydrogenase (LDH), human chorionic gonadotropin (HCG), CA-125, and alpha-fetoprotein (AFP).[12]
CT
It is difficult to distinguish ovarian germ cell tumors on CT alone. Dysgerminoma often appears as multilobulated solid masses with prominent fibrovascular septa while, mature ovarian teratoma may demonstrate fat (areas with very low Hounsfield values), fat-fluid level, calcification (sometimes dentiform), Rokitansky protuberance, and tufts of hair.[4][5][6]
MRI
It is difficult to distinguish subtypes of ovarian germ cell tumor on MRI alone. The majority of ovarian germ cell tumors have a solid and cystic appearance with areas of hemorrhage and necrosis. On MRI, ovarian germ cell tumors may be characterized by T2: the septae are often hypointense or isointense T1 C+ (Gd): the septae often show marked enhancement (dysgerminoma), the presence of a prominent solid component containing calcifications and small foci of fat (mature teratoma), areas of haemorrhage can also be seen (yolk sac tumor).[4][5][6]
Ultrasound
It is difficult to distinguish ovarian germ cell tumors on ultrasound alone. Both solid and cystic lesions with calcification may be present. Dysgerminoma often appears as a hypoechoic mass while other ovarian germ cell tumors often have variable echogenicity. Ovarian teratoma may be further characterized by the presence of sebaceous and hair components arising from the rokitansky protuberance.[4][5][6][13]
Medical Therapy
The mainstay of therapy for ovarian germ cell tumor is chemotherapy.[8][9][10][11]
Surgery
Surgery is the mainstay of treatment for ovarian germ cell tumors.[8][9][10][11]
References
- ↑ Updates in the Management of Ovarian Germ Cell Tumors. http://meetinglibrary.asco.org/content/31-132. URL Accessed on November 11, 2015
- ↑ Cellular Classification of Ovarian Germ Cell Tumors. http://www.cancer.gov/types/ovarian/hp/ovarian-germ-cell-treatment-pdq#section/_. URL Accessed on November 4, 2015
- ↑ 3.0 3.1 Hoffman, Barbara (2012). Williams gynecology. New York: McGraw-Hill Medical. ISBN 9780071716727.
- ↑ 4.0 4.1 4.2 4.3 Ovarian dysgerminoma. http://radiopaedia.org/articles/ovarian-dysgerminoma. URL Accessed on November 11, 2015
- ↑ 5.0 5.1 5.2 5.3 Mature (cystic) ovarian teratoma. http://radiopaedia.org/articles/mature-cystic-ovarian-teratoma. URL Accessed on November 11, 2015
- ↑ 6.0 6.1 6.2 6.3 Ovarian yolk sac tumour. http://radiopaedia.org/articles/ovarian-yolk-sac-tumour. URL Accessed on November 11, 2015
- ↑ Ovarian Germ Cell Tumors Treatment.http://www.cancer.gov/types/ovarian/patient/ovarian-germ-cell-treatment-pdq. URL Accessed on November 11, 2015
- ↑ 8.0 8.1 8.2 Stage I Ovarian Germ Cell Tumors . http://www.cancer.gov/types/ovarian/hp/ovarian-germ-cell-treatment-pdq#section/_33. URL Accessed on Nov 5, 2015
- ↑ 9.0 9.1 9.2 Stage II Ovarian Germ Cell Tumors . http://www.cancer.gov/types/ovarian/hp/ovarian-germ-cell-treatment-pdq#section/_43. URL Accessed on Nov 5, 2015
- ↑ 10.0 10.1 10.2 Stage III Ovarian Germ Cell Tumors . http://www.cancer.gov/types/ovarian/hp/ovarian-germ-cell-treatment-pdq#section/_54. URL Accessed on Nov 5, 2015
- ↑ 11.0 11.1 11.2 Stage IV Ovarian Germ Cell Tumors . http://www.cancer.gov/types/ovarian/hp/ovarian-germ-cell-treatment-pdq#section/_65. URL Accessed on Nov 5, 2015
- ↑ Ovary: Germ cell tumors. http://atlasgeneticsoncology.org/Tumors/OvarianGermCellID5067.html. URL Accessed on November 10, 2015
- ↑ Immature ovarian teratoma. http://radiopaedia.org/articles/immature-ovarian-teratoma. URL Accessed on November 11, 2015