For most patients with gonadal dysgenesis, dysgerminomas arise in gonadoblastomas, which are benign ovarian tumors that are composed of germ cells and sex cord stroma. If gonadoblastomas are left in situ in patients with gonadal dysgenesis, more than 50% will develop into ovarian malignancies (351).
About 65% of dysgerminomas are stage I (i.e., confined to one or both ovaries) at diagnosis (2,3,352–356). About 85% to 90% of stage I tumors are confined to one ovary; 10% to 15% are bilateral. Dysgerminoma is the only germ cell malignancy that has this significant rate of bilaterality. Other germ cell tumors are rarely bilateral.
For patients whose contralateral ovary is preserved, disease can develop in 5% to 10% of the retained gonads over the next 2 years (2). This figure includes those not given additional therapy and patients with gonadal dysgenesis.
In the 25% of patients who are diagnosed initially with metastatic disease, the tumor commonly spreads via the lymphatic system. It can spread hematogenously or by direct extension through the capsule of the ovary with exfoliation and dissemination of cells throughout the peritoneal surfaces. Metastases to the contralateral ovary may be present when there is no other evidence of spread. An uncommon site of metastatic disease is bone; when metastasis to this site occurs, the lesions are principally in the lower vertebrae. Metastases to the lungs, liver, and brain are often in patients with longstanding or recurrent disease. Metastasis to the mediastinum and supraclavicular lymph nodes is usually a late manifestation of disease (352,353).
The treatment of patients with early dysgerminoma is primarily surgical, including resection of the primary lesion and proper surgical staging. Chemotherapy is administered to patients with metastatic disease. Because the disease principally affects girls and young women, special consideration must be given to the preservation of fertility and use of chemotherapy whenever possible. An algorithm for the management of ovarian dysgerminoma is presented in Figure 37.20.
Surgery The minimal surgical operation for ovarian dysgerminoma is a unilateral oophorectomy (354). If there is a desire to preserve fertility, as there almost always is, the contralateral ovary, fallopian tube, and uterus should be left in situ, even in the presence of metastatic disease, because of the sensitivity of the tumor to chemotherapy. If fertility need not be preserved, it may be appropriate to perform a total abdominal hysterectomy and bilateral salpingo-oophorectomy for patients with advanced disease (356). For patients whose karyotype analysis reveals a Y chromosome, both ovaries should be removed, although the uterus may be left in situ for possible future embryo transfer (351). Whereas cytoreductive surgery is of unproved value, bulky disease that can be readily resected (e.g., an omental cake) should be removed during the initial operation.
In patients in whom the neoplasm appears on inspection to be confined to the ovary, a careful staging operation should be undertaken to determine the presence of any occult metastatic disease. All peritoneal surfaces should be inspected and palpated, and any suspicious lesions should be sampled for biopsy. Unilateral pelvic lymphadenectomy and careful palpation and biopsy of enlarged para-aortic nodes are particularly important parts of the staging. These tumors often metastasize to the para-aortic nodes around the renal vessels. Dysgerminoma is the only germ cell tumor that tends to be bilateral, excisional biopsy of any suspicious masses is desirable (354–356). If a small contralateral tumor is found, it may be possible to resect it and preserve some normal ovary.