Mature Cystic Teratoma (

fig. 1a, b). Benign cystic teratomas or dermoid cysts are the most common germ cell tumors and in this case all tissue is mature and there is no mitotic activity. Patients may be asymptomatic or present abdomino-pelvic pain or increasing abdominal girth. Due to the weight of the lesion, there is a potential risk of ovarian torsion. Physical examination may reveal a palpable adnexal mass which may be voluminous. Pelvic X-rays may show pelvic calcifications. Ultrasonography can identify an ovarian heterogeneous solid mass. The type of surgery depends on the volume of the tumor and its sonographic appearance. The aim is optimal preservation of the normal ovary with the minimum of risk of adherence or spillage of cyst fluid. It is important to search for malignant cells and bilateral lesions in the cystectomy specimen. In all cases, the cyst is excised and the remaining normal ovary salvaged. Approximately 10% of teratomas are bilateral and careful sonographic and macroscopic examination of the contralateral ovary is necessary.

However, several studies have found that histologic examination of an apparently normal ovary leads to identification of a teratoma in fewer than 1% of the cases. Under these conditions, several reports agree that routine biopsy of the contralateral ovary is not in fact necessary.

Teratomas are usually benign tumors but their malignant potential is related to the histological differentiation and nuclear atypia of their cells. They can be classified in three types: immature malignant teratomas, mature benign teratomas or monodermal teratomas. Malignancy is determined according to the FIGO classification and the grade adapted for germ cell tumors, with neuroepithelial tissue present in grade 3.

Dysgerminomas. Dysgerminomas are the most frequent malignant germ cell tumors in young women (80% of cases). They are rarely pure dysgerminomas but are often mixed with other cell types and synciotrophoblastic types secreting hCG. They are usually large and often secrete hormones and tumor markers such as β-hCG, LDH or αFP, which can be useful in monitoring the course of the disease. Paraneoplastic manifestations are possible. Diagnosis is often made at stage 1A and conservative surgery with salpingo-oophorectomy is the treatment of choice. These tumors are bilateral in 20% of cases and surveillance of the contralateral ovary with systematic biopsy is recommended.

Localized, unilateral forms have an excellent prognosis at 5 years but there is a high recurrence rate. The prognosis is more reserved in mixed bilateral forms with multiple recurrences and an endodermal sinus component.

Among the tumors with an unfavorable prognosis are those >10 cm in diameter and with more than one-third mixed component. These tumors are sensitive to chemotherapy and radiotherapy. Chemotherapy protocols are indicated in the more extensive forms (FIGO stages II, III and beyond).

Endodermal Sinus Tumors or Yolk Sac Tumors. These are an association of extra-embryonic mesodermal cells and endodermal cells. The mean age at diagnosis is 19 years and the incidence appears to increase with age. These tumors evolve very rapidly and are only exceptionally bilateral. There are four architectural variants: labyrinthine, pseudo-papillary, polyvesicular and solid.

αFP is an excellent marker for diagnosing recurrences, which occur very frequently during the first year. Polychemotherapy protocols have markedly improved survival.

Other Tumors. Other tumors include embryonic carcinomas consisting of extra-embryonic and embryonic teratoma-type pluripotential cells. Choriocarcinomas are biphasic tumors composed of cytotrophoblasts and syncytiotrophoblasts secreting β-hCG and αFP.