Ovarian germ cell tumors: Pathology, epidemiology, clinical manifestations, and diagnosis

INTRODUCTION — Ovarian germ cell tumors (OGCTs) are derived from primordial germ cells of the ovary (figure 1). They may be benign (eg, mature teratoma) or malignant (eg, immature teratoma, dysgerminoma, yolk sac tumor, mixed germ cell neoplasm).

The pathology, epidemiology, clinical manifestations, and diagnosis of OGCTs, as well as the treatment of benign OGCTs are reviewed here. Treatment of malignant OGCTs as well as clinical features, diagnosis, and treatment of epithelial ovarian carcinoma are discussed separately. (See "Treatment of malignant germ cell tumors of the ovary" and "Overview of epithelial carcinoma of the ovary, fallopian tube, and peritoneum".)

TYPES — The histologic types of OGCTs that arise from the ovary are similar to those developing in the testes of males (table 1) [1,2]. (See "Anatomy and pathology of testicular tumors".)

OGCTs can be broadly divided into those that differentiate toward embryo-like neoplasms (eg, teratomas and their subtypes, dysgerminomas) and those that differentiate primarily toward extraembryonic fetal-derived (placenta-like) cell populations or a mixture of both. Categories include:

●Teratomas – The designation teratoma refers to a neoplasm that differentiates toward somatic-type cell populations (typically including cell populations that would normally derive from ectoderm, endoderm, and mesoderm) that can be typical of either adult or embryonic development and are foreign to the anatomic site in which they are found. They are divided into four categories:

•Mature (cystic or solid, benign)

•Immature (malignant)

•Malignant due to a component of another somatic malignant neoplasm

•Monodermal or highly specialized

●Dysgerminomas – These are the female version of the male seminoma and are essentially comprised of immature germ cells. (See "Anatomy and pathology of testicular tumors".)

●Yolk sac tumors – These are carcinomas (epithelial neoplasms) that differentiate toward yolk sac/primitive placenta forms (also called endodermal sinus tumors).

●Mixed germ cell tumors – These are tumors with two or more types of malignant OGCTs. The most common combination is a dysgerminoma and yolk sac tumor.

●Rare OGCTs – Rare OGCTs include:

•Pure embryonal carcinomas

•Nongestational choriocarcinomas

•Pure polyembryoma

EPIDEMIOLOGY — OGCTs comprise approximately 20 to 25 percent of ovarian neoplasms overall, but only account for about 5 percent of all malignant ovarian neoplasms [1,3,4].

OGCTs are found primarily in young females between 10 and 30 years of age, representing 70 percent of ovarian neoplasms in this age group [5]. Worldwide, the incidence is the highest in Eastern Asia for females <30 years, and the highest in Central America for those >30 years [6]. For unclear reasons, in the Surveillance, Epidemiology, and End Results (SEER) United States national cancer database, malignant OGCTs occurred more frequently among Hispanic Americans and Asian/Pacific Islanders compared with non-Hispanic White and non-Hispanic Black Americans [7].

Among malignant OGCTs, dysgerminoma, immature teratoma, yolk sac tumors, and mixed germ cell tumors account for 90 percent of cases [1,4]. The distribution of histologic types among malignant ovarian germ cell tumors is found in the table (table 2) and discussed in detail below. (See 'Histopathology and clinical behavior' below.)

CLINICAL PRESENTATION

Nonspecific signs and symptoms — Patients may be asymptomatic or present with one or more of the following signs and symptoms [8-12]:

●Abdominal enlargement – OGCTs tend to grow rapidly, and abdominal enlargement may occur from the mass itself, ascites, or both. OGCTs tend to be large (median size, 16 cm), and ascites is reported in 20 percent of cases.

●Abdominal pain – From rupture or torsion. Rupture (pre- or intraoperative) and torsion are reported in 20 and 5 percent of cases, respectively. The pain may be acute and can be misdiagnosed as appendicitis.

●Precocious puberty – Presumably from human chorionic gonadotropin (hCG) production.

●Symptoms of pregnancy – From hCG production.

●Other – Other symptoms, such as fever or vaginal bleeding, occur in approximately 10 percent of patients.

Abdominal pain and an abdominal mass are present in most (85 percent) patients with an OGCT [13].

Signs and symptoms characteristic of a specific OGCT — While most ovarian germ cell tumors (OGCTs) present with nonspecific signs or symptoms, some presentations are more specific for certain OGCTs. For example, rupture of a mature teratoma with spillage of sebaceous material into the abdominal cavity can present with shock. By contrast, monodermal highly specialized teratomas usually present with hyperthyroidism or carcinoid symptoms (table 3). (See 'Mature teratoma (dermoid)' below and 'Monodermal highly specialized teratomas' below.)

Rare presentations — Anti-N-methyl-D-aspartate receptor encephalitis is a rare condition associated with either mature or immature teratomas [14]. (See "Autoimmune (including paraneoplastic) encephalitis: Clinical features and diagnosis", section on 'Anti-NMDA receptor encephalitis'.)

DIAGNOSTIC EVALUATION — The diagnostic evaluation is similar to that of patients with other adnexal masses and includes a complete medical history and physical examination. (See "Approach to the patient with an adnexal mass", section on 'Diagnostic evaluation'.)

Imaging — As with other adnexal masses, pelvic ultrasound is typically the first-line imaging study used to characterize an adnexal mass, though patients with an acute presentation may be initially imaged with computed tomography. (See 'Nonspecific signs and symptoms' above and "Adnexal mass: Ultrasound categorization".)

Laboratory testing

Tumor markers — OGCTs often produce hormones, which can be measured in the serum, providing a highly sensitive and variably specific marker for the presence of certain histologic components (table 4). Some tumor markers are present in some, but not all, tumors of a specific histology. As an example, tumor markers produced by tumor types may include:

●human chorionic gonadotropic (hCG) – Embryonal cell carcinomas and ovarian choriocarcinomas, mixed germ cell tumors, and some dysgerminomas.

●Alpha-fetoprotein (AFP) – Yolk sac tumors, embryonal cell carcinomas and polyembryoma carcinomas, mixed germ cell tumors, and some immature teratomas [15,16]; most dysgerminomas are associated with a normal AFP.

●Lactate dehydrogenase (LDH) – Dysgerminomas.

If elevated, tumor markers are useful for monitoring the response to treatment and for posttreatment surveillance.

Other — A pregnancy test should be performed for all reproductive-age patients to exclude an ectopic pregnancy or other pregnancy-related adnexal mass. (See "Adnexal mass: Differential diagnosis", section on 'Pregnancy-related'.)

DIAGNOSIS — The diagnosis of OGCTs is made by histology at time of surgical excision. The diagnosis is strongly suggested preoperatively by the presence of an adnexal mass on pelvic imaging and an elevated level of an associated tumor marker. (See 'Imaging' above and 'Tumor markers' above.)

For benign cystic mature teratomas, the diagnosis can be made with reasonable confidence using pelvic ultrasonography; however, removal of the cyst is still advised. (See 'Mature teratoma (dermoid)' below and "Adnexal mass: Ultrasound categorization", section on 'Mature teratoma'.)

HISTOPATHOLOGY AND CLINICAL BEHAVIOR

Teratomas

Mature teratoma (dermoid) — Most teratomas are cystic (mature cystic teratoma; dermoid cyst) and are composed of mature differentiated elements including tissue of ectodermal (eg, skin, hair follicles, sebaceous glands), mesodermal (eg, muscle, urinary), and endodermal (eg, lung, gastrointestinal) origin [17]. The mechanism by which these cysts develop is possibly by failure of meiosis II or from a premeiotic cell in which meiosis I has failed [18]. In rare instances, a teratoma is solid but is composed entirely of benign-appearing heterogeneous collections of tissue and organized structures derived from all three cell layers.

Mature cystic teratomas account for more than 95 percent of all ovarian teratomas are the most common ovarian tumor in females in the second and third decade of life [19]. Mature teratomas at nonovarian sites (eg, vaginal wall) have also been described [20].

The characteristic macroscopic appearance of a benign cystic teratoma is a multicystic mass that contains hair, teeth, and/or skin that is mixed into sebaceous, thick, sticky, and often foul-smelling material (picture 1). A solid prominence (Rokitansky protuberance) is located at the junction between the teratoma and normal ovarian tissue [1]. The greatest cellular variety is found in the area of this junction, which should therefore be examined carefully by the pathologist to exclude immature/malignant components.

Most patients with mature teratomas are asymptomatic. If present, symptoms depend on the size of the mass. Torsion is not uncommon. Rupture of dermoid cysts with spillage of sebaceous material into the abdominal cavity can occur, but is uncommon. Shock and hemorrhage are the immediate sequelae of rupture; a marked granulomatous reaction (chemical peritonitis) may subsequently develop and lead to formation of dense adhesions.

Most mature solid teratomas are unilateral. Bilateral mature teratomas occur in 10 to 17 percent of cases (table 5) and can be synchronous and metachronous [21]; peritoneal implants have also been described [22]. Grossly, it may be difficult/impossible to differentiate these neoplasms from malignant solid immature teratomas, which are almost always solid, and they therefore may require sampling from multiple sites. (See 'Immature teratoma' below.)

Malignant transformation — Mature teratomas are almost always benign [19]. Development of malignant (somatic) neoplasm occurs in 0.2 to 2 percent of mature cystic teratomas [23-25], and comprises 2.9 percent of all malignant OGCTs (table 2) [26]. Although any of the components of a mature cystic teratoma may develop malignant neoplasm, squamous cell carcinoma arising from the ectoderm is the most common secondary neoplasm [22,27]. Other possible malignant neoplasms include (but are not limited to) basal cell carcinoma, melanoma, adenocarcinoma, sarcoma, and thyroid carcinoma. When malignant transformation has occurred within a teratoma, treatment must be tailored to the transformed histology.

Risk factors for malignant neoplasm in a mature cystic teratoma include age over 45 years (mean age, 50 years versus 33 years for benign teratomas), tumor diameter >10 cm, rapid growth, and characteristic findings on imaging (eg, low-resistance intratumor flow on Doppler) [22,27]. (See "Adnexal mass: Ultrasound categorization", section on 'Mature teratoma'.)

Immature teratoma — Immature teratomas (also called malignant teratoma, teratoblastoma, or embryonal teratoma) comprise less than 1 percent of ovarian teratomas and are most common in the first two decades of life [17]. They comprise 35.6 percent of all malignant OGCTs (table 2) [26].

Immature teratomas are typically composed of tissue from the three germ cell layers: ectoderm, mesoderm, and endoderm, arranged in a haphazard manner. Histologically, there are varying amounts of immature tissue, most frequently with neural differentiation, although immature stromal elements can also be present.

Immature teratomas are the only OGCTs that are histologically graded. The grade of differentiation (ranging from I [well differentiated] to III [poorly differentiated]) is based on the proportion of tissue in histologic sections containing immature neural elements [8]. Grade is an important indicator of the risk for extraovarian spread. The presence of foci of yolk sac tumor in immature teratomas generally reflects more aggressive behavior and a worse outcome [28]. (See 'Yolk sac tumor' below.)

Monodermal highly specialized teratomas — The specialized or monodermal teratomas are a rare and remarkable subset of teratomas that consist of a predominant mature histologic cell type. The most common of these are struma ovarii and carcinoid (a well-differentiated neuroendocrine neoplasm). They are usually unilateral, although a contralateral teratoma may be present.

●Struma ovarii – Struma ovarii is a teratoma predominantly composed of mature thyroid tissue [17]. The secretion of thyroid hormones results in clinical hyperthyroidism in 25 to 35 percent of such patients.

Struma ovarii is uncommon, comprising approximately 2.7 percent of ovarian teratomas. It is often associated with a mature cystic teratoma and rarely with a cystadenoma. Most cases of struma ovarii are benign and can be managed by excision of the ovary or by unilateral salpingo-oophorectomy. However, malignant change may occur, but it is exceedingly rare [29,30]. (See "Struma ovarii".)

●Carcinoid neoplasms – Ovarian carcinoid neoplasms are rare [31]. Primary ovarian carcinoid neoplasms are usually unilateral, localized to the ovary, and indistinguishable histologically from metastasis. They have similar appearances to those that arise in any other site (eg, gastrointestinal, respiratory). They are comprised of nests and cords of relatively bland cells (uniform cells without nuclear atypia) with endocrine features and a fine vascular network.

Some carcinoid neoplasms secrete bioactive polypeptides and amines, producing a constellation of symptoms, predominantly flushing and diarrhea (table 3). Carcinoid syndrome develops in approximately one-third of cases, and it can develop without hepatic metastases due to direct venous drainage from the ovary into the systemic circulation (see "Clinical characteristics of well-differentiated neuroendocrine (carcinoid) tumors arising in the gastrointestinal and genitourinary tracts", section on 'Ovary' and "Clinical features of carcinoid syndrome", section on 'Clinical features'). 5-hydroxyindoleacetic acid, a metabolite of serotonin (figure 2), is excreted in the urine and can be used to confirm the diagnosis of carcinoid syndrome and as a marker of disease activity in patients with advanced disease or the carcinoid syndrome. (See "Diagnosis of carcinoid syndrome and tumor localization", section on 'Biochemical testing for carcinoid syndrome'.)

Carcinoid tumors metastatic to the ovary are even more rare; they tend to be bilateral and arise from primary ileal carcinoid tumors [32]. In such cases, disseminated abdominal disease is common.

●Mixed struma ovarii and carcinoid – The presence of a mixed struma ovarii and carcinoid is even more rare. These lesions usually follow a benign course.

Dysgerminoma — Although dysgerminomas are relatively uncommon among all ovarian neoplasms (accounting for only an approximate 2 percent), they account for 33 percent of malignant OGCTs (table 2) [26]. The majority of cases (75 percent) arise in adolescents and young females, in whom they account for approximately one-third of all ovarian malignant neoplasms [33]. As such, they are one of the more common ovarian malignant neoplasms detected during pregnancy. Nevertheless, dysgerminoma can occur at any age; case reports have described patients with dysgerminoma between 7 months and 70 years of age.

Although dysgerminomas are malignant, the degree of histologic atypia is variable, and only an approximate one-third behave aggressively. The neoplasm is composed of undifferentiated germ cells, large vesicular cells with clear cytoplasm, well-defined cell boundaries, and centrally placed regular nuclei; the overall appearance is sometimes described as resembling "fried eggs" (picture 2). The stroma is infiltrated by clusters of small lymphocytes and frequently contains granulomas. Dysgerminoma is the ovarian counterpart of testicular seminoma, and histologically it has a similar appearance (see "Anatomy and pathology of testicular tumors"). Grossly, dysgerminoma appears as a lobulated mass that is firm and cream colored or pale tan (picture 3) [1].

The growth of dysgerminomas is usually rapid; as a result, patients often present with abdominal enlargement and pain due to rupture with hemoperitoneum or torsion. Menstrual abnormalities may occur if the tumor is hormonally active. Dysgerminomas can contain syncytiotrophoblastic giant cells that produce placental alkaline phosphatase, and lactate dehydrogenase (LDH) [34,35]. Serial measurements of these markers can be useful for monitoring disease (table 4). In addition, human chorionic gonadotropin (hCG) is produced in 3 to 5 percent of dysgerminomas [36]. In general, dysgerminomas do not produce alpha-fetoprotein (AFP), although borderline elevations (<16 ng/mL) are described in case series, but most often in the setting of mixed germ cell tumors that contain a yolk sac element [12].

Bilateral ovarian disease is more common with dysgerminoma than with any other malignant OGCT. While 75 percent of patients with dysgerminomas present with stage I disease (table 6), the contralateral ovary is involved in 10 to 15 percent of cases (table 5) [37,38].

Association with gonadoblastoma — Dysgerminomas may develop within a gonadoblastoma (a benign or in situ germ cell ovarian neoplasm composed of germ cells and sex cord stroma) in phenotypic females who have a Y chromosome. Included in this group are patients with pure gonadal dysgenesis (46XY), mixed gonadal dysgenesis (45X/46XY), or complete androgen insensitivity (formerly called testicular feminization; 46XY). Occasional patients may have features of Turner syndrome. These latter patients may have a 45X, 45X/46XX, or 45X/46XY karyotype. (See "Clinical manifestations and diagnosis of Turner syndrome", section on 'Risk of malignancy'.)

These tumors may produce either testosterone or estrogens. Clinical presentation may include developmental abnormalities of the genitalia, primary amenorrhea, or virilization. Although gonadoblastoma may be overgrown by dysgerminoma, as occurs in approximately 50 percent of cases, other malignant germ cell components may predominate, including yolk sac tumor, immature teratoma, embryonal carcinoma, or choriocarcinoma. Thus, karyotyping is recommended for all patients with the operative finding of gonadoblastoma, with or without a coexistent malignant germ cell tumor, or young patients who present with an ovarian mass or masses and either primary amenorrhea or abnormalities of the genitalia.

It is important to determine whether a gonadoblastoma is present, since oophorectomy should be performed in these patients to prevent the development of gonadal neoplasia, although the age at which the procedure is performed depends upon the underlying etiology [39,40]. Patients at risk for having dysgenetic gonads ideally should be identified preoperatively; frozen section is not reliable.

Yolk sac tumor — Yolk sac tumors (also known as endodermal sinus tumors) make up 14 to 20 percent of all malignant OGCTs (table 2) [26,41]. These neoplasms usually occur in young females; the median age at presentation is 23 years and one-third of patients are premenarchal [42,43].

Histologically, these epithelial neoplasms consist of tubules or spaces lined by single layers of flattened cuboidal cells, reticular stroma, and scattered globules (picture 4) [9]. Invaginated papillary structures with a central vessel (Schiller-Duval bodies) are found within some of the spaces (picture 5) [1].

Tumor growth can be very rapid and aggressive with extensive intraperitoneal dissemination.

Mixed germ cell tumors — Mixed germ cell neoplasms account for 5.3 percent of all malignant OGCTs (table 2) [26]. They consist of two or more admixed types of OGCTs; components of dysgerminoma mixed with a yolk sac tumor are found most commonly.

In cases in which a dysgerminoma component is present, the contralateral ovary is involved 10 percent of the time. The neoplasms may secrete tumor markers, such as lactate dehydrogenase, alpha-fetoprotein, or human chorionic gonadotropin, depending upon the type of tissue present.

Embryonal carcinoma — Embryonal carcinoma accounts for 4 percent of malignant OGCTs (table 2) [26,44]. It resembles the more common embryonal carcinoma of the testis and is one of the most aggressive ovarian malignant neoplasms. The average age at diagnosis is 15 years. (See "Anatomy and pathology of testicular tumors".)

Histologically, embryonal carcinomas are epithelial and therefore form nests and sometimes papillary or gland-like structures. Many atypical mitotic figures are usually present, reflecting the high proliferative activity of the neoplastic cells. Multinucleated giant cells resembling syncytial cells may be present; these are the cells that produce hCG [17]. Some embryonal carcinomas also make AFP (table 4).

Clinically, they usually present with an abdominal or pelvic mass and abdominal pain [13].

Choriocarcinoma — Nongestational choriocarcinoma is a rare and highly malignant type of OGCT [45]. Choriocarcinomas are more commonly of placental than ovarian origin; the estimated incidence of a primary ovarian choriocarcinoma is 1 in 369,000,000. They comprise 2.1 percent of all malignant OGCTs (table 2) [26]. A choriocarcinoma of ovarian origin derives from an extraembryonic differentiation of malignant germ cells. This highly malignant germ cell epithelial neoplasm differentiates towards trophoblastic structures and often contains other malignant germ cell elements.

Nongestational ovarian choriocarcinoma is histologically identical to primary gestational choriocarcinoma associated with pregnancy [46-48]. The two entities can be distinguished by DNA analysis; the presence of paternal DNA within the tumor indicates a gestational (placental) origin [49]. (See "Gestational trophoblastic disease: Pathology", section on 'Choriocarcinoma'.)

All choriocarcinomas produce hCG, which may cause isosexual precocity in young girls and irregular vaginal bleeding of uterine origin. Serum levels of hCG are useful for monitoring response to treatment.

Like gestational choriocarcinomas, those arising in the ovary tend to develop early hematogenous metastasis to several different sites, including lung, liver, brain, bone, vagina, and other viscera. In contrast to gestational choriocarcinomas, those arising in the ovary are relatively chemoresistant.

Polyembryoma — Polyembryoma is a malignant germ call neoplasm that is very rare and, in most instances, is associated with other germ cell elements such as immature teratoma. It is composed of embryoid bodies that morphologically resemble normal embryos [1].

It usually occurs in young females and may present with signs of pseudopuberty as serum hCG and AFP concentrations can be elevated.

STAGING AND SURGICAL TREATMENT — In virtually all cases of OGCTs, surgery is required for definitive histologic diagnosis, treatment, and staging (if malignant). Oophorectomy, ovarian cystectomy, or resection of the ovarian mass can be performed, depending on the clinical situation, and tissue sent for frozen section. Confirmation of the diagnosis should be obtained prior to definitive surgical treatment.

Most patients with OGCTs present with stage IA disease (limited to one ovary); bilateral disease occurs in 10 to 12 percent of cases [50]. Tumors with a propensity for bilateral ovarian involvement include benign cystic teratoma, dysgerminoma, or a tumor with components of dysgerminoma (mixed germ cell tumor).

Mature cystic teratomas — For most patients with a mature cystic teratoma, ovarian cystectomy is suggested to make a definitive diagnosis, preserve ovarian tissue, and avoid potential problems such as torsion, rupture, or development of malignant components. For patients who have completed childbearing, salpingo-oophorectomy is also acceptable treatment. Benign cystic teratomas do not recur if surgically resected.

Mature cystic teratomas may be removed via either laparoscopy or laparotomy. While intact removal is preferred, rupture can occur, and the abdomen should be copiously irrigated to avoid a chemical peritonitis from any spillage of the sebaceous cyst fluid. (See "Oophorectomy and ovarian cystectomy", section on 'Laparoscopic/minimally invasive surgery cystectomy'.)

All other OGCTs (malignant) — Malignant germ cell tumors are staged according to the International Federation of Gynecology and Obstetrics (FIGO) staging system for epithelial ovarian cancer (table 6) [51]. In brief, stage I disease is confined to the ovaries, stage II includes extension into other pelvic tissues, stage III refers to disease that has spread beyond the pelvis or to retroperitoneal lymph nodes but remains in the abdomen, and stage IV refers to the presence of distant metastasis or involvement of liver parenchyma.

Management of malignant OGCTs is discussed in detail separately. (See "Treatment of malignant germ cell tumors of the ovary".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Ovarian, fallopian tube, and peritoneal cancer".)

SUMMARY AND RECOMMENDATIONS

●Types – Ovarian germ cell tumors (OGCTs) are derived from primordial germ cells of the ovary (figure 1). They may be benign or malignant. The histologic types of OGCTs can be found in the table (table 1). (See 'Introduction' above and 'Types' above.)

●Epidemiology – OGCTs comprise approximately 20 to 25 percent of ovarian neoplasms overall, but account for only an approximate 5 percent of all malignant ovarian neoplasms. They arise primarily in young patients between 10 and 30 years of age and represent 70 percent of ovarian neoplasms in this age group. (See 'Epidemiology' above.)

The distribution of histologic types among malignant ovarian germ cell tumors is found in the table (table 2). (See 'Epidemiology' above.)

●Clinical presentation – Patients may be asymptomatic or present with nonspecific symptoms such as abdominal enlargement, abdominal pain, precocious puberty, symptoms of pregnancy, fever, and/or vaginal bleeding. Abdominal pain and an abdominal mass are present in most patients. (See 'Nonspecific signs and symptoms' above.)

Other presentations may be specific for certain OGCTs (eg, rupture of a mature teratoma can present with shock, monodermal highly specialized teratomas usually present with hyperthyroidism or carcinoid symptoms (table 3)). (See 'Signs and symptoms characteristic of a specific OGCT' above.)

●Diagnostic evaluation –The diagnostic evaluation is similar to that of patients with other adnexal masses, and includes a complete medical history, physical examination, and pregnancy test in reproductive-age patients. (See 'Diagnostic evaluation' above and 'Other' above.)

•As with other adnexal masses, pelvic ultrasound is typically the first-line imaging study used. (See 'Imaging' above.)

•OGCTs often produce tumor markers (eg, human chorionic gonadotropin [hCG], alpha-fetoprotein [AFP], lactate dehydrogenase [LDH] (table 4)), providing a highly sensitive and variably specific marker for the presence of certain histologic components. (See 'Tumor markers' above.)

●Diagnosis – The diagnosis of OGCTs is made by histology at time of surgical excision. The diagnosis is strongly suggested preoperatively by the presence of an adnexal mass on pelvic imaging and an elevated level of an associated tumor marker (table 4), if present. (See 'Diagnosis' above.)

The diagnosis of a benign cystic mature teratoma is also strongly suggested by characteristic findings on pelvic ultrasonography. (See 'Diagnosis' above.)

●Mature teratoma – The most common OGCT is the benign mature cystic teratoma (dermoid cyst), which can be bilateral. Approximately 1 percent contain a secondary malignancy arising from one of the components, usually a squamous cell cancer. Ovarian cystectomy or oophorectomy provides definitive diagnosis and treatment. (See 'Mature teratoma (dermoid)' above.)

●Dysgerminoma – Dysgerminoma is the most common malignant ovarian germ cell tumor. Bilateral ovarian disease is more common than with any other ovarian germ cell tumor. These tumors are less likely to produce tumor markers than other malignant germ cell tumors (table 4), but LDH is often elevated. (See 'Dysgerminoma' above.)