Immature teratoma

A teratoma is a tumor of germ cell origin, containing tissues from more than one germ cell line. It can be ovarian or testicular in its origin. A teratoma is a tumor of germ cell origin, containing tissues from more than one germ cell line. It can be ovarian or testicular in its origin. An ovarian teratoma is a tumor that arises from egg cells in the ovary. Histologically, it is of two types: mature cystic teratoma and immature teratoma. A mature cystic teratoma, often called a dermoid cyst, is a benign non-cancerous tumor. Malignant transformation (most often to squamous cell carcinoma) is observed only in rare cases. A mature cystic teratoma is most frequently diagnosed in women during their reproductive ages, but can occur in women of all age groups. Treatment options for mature cystic teratomas include cystectomy or unilateral salpingo-oophorectomy. An immature teratoma is a very rare tumor, representing 1% of all teratomas, 1% of all ovarian cancers, and 35.6% of malignant ovarian germ cell tumors. It displays a specific age of incidence, occurring most frequently in the first two decades of life and almost never after menopause. Unlike a mature cystic teratoma, an immature teratoma contains immature or embryonic structures. It can coexist with mature cystic teratomas and can constitute of a combination of both adult and embryonic tissue. The most common symptoms noted are abdominal distension and masses. Prognosis and treatment options vary and largely depend on grade, stage and karyotype of the tumor itself. At CT and MRI, an immature teratoma possesses characteristic appearance. It is typically large (12–25 cm) and has prominent solid components with cystic elements. It is usually filled with lipid constituents and therefore demonstrates fat density at CT and MRI. Ultrasound appearance of an immature teratoma is nonspecific. It is highly heterogeneous with partially solid lesions and scattered calcifications. Traditionally, comprehensive surgical staging is performed via exploratory laparotomy with cytologic washings, peritoneal biopsies, an omental assessment (either biopsy or rarely a full omentectomy), and both pelvic and aortic lymph node dissection. Laproscopy is often suggested as an alternative to surgically stage patients with immature teratoma. Ovarian cancer is staged using the FIGO staging system and uses information obtained after surgery, which can include a total abdominal hysterectomy via midline laparotomy, unilateral (or bilateral) salpingo-oophorectomy, pelvic (peritoneal) washings, assessment of retroperitoneal lymph nodes and/or appendectomy. The AJCC staging system, identical to the FIGO staging system, describes the extent of tumor (T), the presence of absences of metastases to lymph nodes (N), the presence or absence of distant metastases (M). An immature teratoma contains varying compositions of adult and embryonic tissue. The most common embryonic component identified in immature teratomas is the neuroectoderm. Occasionally, tumors may present neuroepithelium that resemble neuroblasts. Tumors may also present embryonic components such as immature cartilage and skeletal muscle of mesodermal origin. Immature teratomas composed of embryonic endodermal derivatives are rare. Often a mature cystic teratoma is misdiagnosed as its immature counterpart due to the misinterpretation of mature neural tissue as immature. While mature neural cells have nuclei with uniformly dense chromatin and neither exhibit apoptotic or mitotic activity, immature neural cells have nuclei with vesicular chromatin and exhibit both apoptotic and mitotic activity. A recent study has identified the use of Oct-4 as a reliable biomarker for the diagnosis of highly malignant cases of immature teratomas.