Ovarian germ cell tumor overview

# Overveiw
Ovarian germ cell tumors is a disease in which malignancy originates from the germ cells of the ovary. Ovarian germ cell tumors are rare, accounting for 2% to 3% of all ovarian cancers. The median age for diagnosis differs for each sub-type of germ cell tumor. World health organization (WHO) classified germ cell tumors into 7 types based on histology. 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 tumors must be differentiated from other neoplastic ovarian masses that can present with similar complaints  non-neoplastic ovarian mass, and adnexal mass. Symptoms of ovarian germ cell tumors include abdominal distention, acute/ subacute abdominal pain, menstrual irregularities, and precocious puberty. The laboratory findings associated with ovarian germ cell tumors include rise in 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 with biopsy not only to distinguish between the subtypes of ovarian germ cell tumors but also for diagnosis confirmation. Surgery along with chemotherapy are the mainstay of treatment depending on the staging of the tumor.

# Historical Perspective
There is limited information about the historical perspective of ovarian germ cell tumors.

# 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. Their common origin is believed to be from 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 %. 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%.

# Diagnosis

## 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: elevated serum level of lactate dehydrogenase (LDH),  human chorionic gonadotropin (HCG), CA-125, and alpha-fetoprotein (AFP).

## CT
It is difficult to distinguish ovarian germ cell tumors on CT alone, however, pelvic/abdominal CT scan may be helpful in the diagnosis. Sensitive findings on CT scan for the diagnosis of mature teratoma include Fat attenuation, presence or absence of calcification in the cyst wall, palm-tree like protrusion, and fat-fluid levels. Presence of cauliflower appearance with irregular borders may warrant the necessity to search for malignant transformation of these tumors. CT scan findings characteristics of immature teratoma include A large, irregular solid mass, presence of coarse calcification, small foci of fat, and Hemorrhage. CT findings associated with other ovarian germ cell tumors are not specific, but may be helpful.

## MRI
Abdominal/pelvic MRI may be helpful in the diagnosis of ovarian germ cell tumors. Findings on MRI suggestive of ovarian germ cell tumors include masses with a cystic and solid component and may contain fat, calcification, fat-fluid level, Tuft\Hairs, Palm tree-like protrusion, and Dermoid nipples-like elements (Rokitansky nodules). The majority of ovarian germ cell tumors have a solid and cystic appearance with areas of hemorrhage and necrosis. The predominance of cystic or solid component differs for each tumor.

## 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.

# Treatment

## Chemotherapy
Adjuvant Chemotherapy is recommended for all the patients with diagnosed malignant ovarian germ cell tumor, except those with stage 1a, stage 1a, 1b dysgerminoma, and grade 1 immature teratomas. The platinum-based regimen is currently the most effective management.

## Radiotherapy
Among ovarian germ cell tumors, only dysgerminoma is radiosensitive. Radiotherapy is not anymore the first option of treatment for dysgerminoma considering its association with ovarian failure development.

## Surgery
Surgical intervention is the mainstay of management of ovarian germ cell tumors. Surgery must be done for the purpose of staging and maybe treatment according to the stage of the tumor. Surgical management of the ovarian germ cell tumors, for the purpose of treatment, classified to two categories according to the preference of the patient to preserve the ovary or not. Surgery is the mainstay of treatment for mature teratoma.