Semiquantification of immature neuroepithelium correlates with survival in ovarian immature teratoma and is the basis for grading of these tumors (377–379). Those with less than one low power field (X 4) of immature neuroepithelium on the slide with the greatest amount of such tissue (grade 1) have a survival of at least 95%, whereas greater amounts of immature neuroepithelium (grades 2 and 3) appear to have a lower overall survival (approximately 85%) (379). This may not apply to immature teratomas of the ovary in children because they have a good outcome with surgery alone, regardless of the degree of immaturity (380,381). The significant inter-and intraobserver difficulty with a three-tier system led some authorities to recommend the two-tier grading system in use, with immature teratomas categorized as either low grade or high grade (377). Immature ovarian teratomas may be associated with gliomatosis peritonei, a favorable prognostic finding if composed of completely mature tissues; reports using molecular methods indicate these glial implants are not tumor derived but represent teratomainduced metaplasia of pluripotent m¨ullerian stem cells in the peritoneum (382,383).
Somatic malignant change in benign cystic teratomas was recorded as occurring in 0.5% to 2% of cases, usually in patients older than 40 years of age (377). The most common malignancy developing in the initially benign teratoma is squamous cell carcinoma. Other neoplasms were reported (e.g., adenocarcinomas, melanomas, which may arise from the skin or retinal anlage, and sarcomas, including leiomyosarcomas and mixed mesodermal tumors) (2). Carcinomas may arise from any of the epithelial elements.
The preoperative evaluation and differential diagnosis of immature teratomas are the same as for other germ cell tumors. Some of these lesions will contain calcifications similar to those of mature teratomas, which can be detected by a radiograph of the abdomen or by ultrasonography. Rarely they are associated with the production of steroid hormones and can be accompanied by sexual pseudoprecocity (342). Tumor markers are negative unless a mixed germ cell tumor is present.
Surgery In a premenopausal patient whose lesion appears to be confined to a single ovary, unilateral oophorectomy and surgical staging should be performed. For a postmenopausal patient, a total abdominal hysterectomy and bilateral salpingo-oophorectomy may be performed. Contralateral involvement is rare, and routine resection or wedge biopsy of the contralateral ovary is unnecessary (3,378,379). Any lesions on the peritoneal surfaces should be sampled and submitted for histologic evaluation. The most frequent site of dissemination is the peritoneum and, much less commonly, the retroperitoneal lymph nodes. Blood-borne metastases to organ parenchyma, such as the lungs, liver, or brain, are uncommon. When present, they are usually seen in patients with late or recurrent disease and most often in tumors that are poorly differentiated (i.e., grade 3).
It is unclear whether debulking of metastatic implants enhances the response to combination chemotherapy (384–390). Unlike epithelial lesions, immature teratomas are chemosensitive. Because cure depends on the prompt delivery of chemotherapy, any surgical resection that is potentially morbid and could delay chemotherapy should be resisted.