Pathophysiology
Teratomas
Outcomes
When considered alone, the two most important clinical variables for predicting outcome in neuroblastoma patients are the disease stage and the patient age at diagnosis. Disease free survival of all patients with stages 1, 2, or 4S is 75-90%. Infants less than one year of age with stage 3 and 4 have cure rates of 80-90% and 60-75%, respectively. Those children older than one year of age with stage 3 and 4 disease have 3-year survivals of 50% and 15%, respectively.
The word teratoma comes from classical Greek and means roughly "monstrous tumor".
A teratoma is an encapsulated tumor with tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable. The tissues of a teratoma, although normal in themselves, may be quite different from surrounding tissues, and may be highly disparate; teratomas have been reported to contain hair, teeth, bone and very rarely more complex organs such as eye, torso, and hands, feet, or other limbs. Usually, however, a teratoma will contain no organs but rather one or more tissues normally found in organs such as the brain, thyroid, liver, and lung. Sometimes, the teratoma has within its capsule one or more fluid-filled cysts and when a large cyst occurs there is a potential for the teratoma to produce a structure within the cyst that resembles a fetus. Because they are encapsulated, teratomas are usually benign, although several forms of malignant teratoma are known and some of these are common forms of teratoma. A mature teratoma is typically benign and found more commonly in females, while an immature teratoma is typically malignant and is more often found in males.
Teratomas are thought to be present at birth (congenital), but small ones often are not discovered until much later in life.
Teratomas belong to a class of tumors known as non-seminomatous germ cell tumor (NSGCT). The term "malignant teratoma" has sometimes been used as a synonym for NSGCT.
All tumors of this class are the result of abnormal development of pluripotent (totipotential) cells: germ cells and embryonal cells.
Teratomas of embryonal origin are congenital; teratomas of germ cell origin may or may not be congenital (this is not known).
Primordial germ cells appear during the third week of gestation in the wall of the yolk sac near the allantois. They move along the dorsal mesentery of the hindgut, reaching the genital ridges by about the sixth week of gestation. Germ cells that do not complete this journey can develop into teratomas. While the totipotential nature of germ cells and their path of migration explain the location and pathology of the more common teratomas (sacroccygeal and gonadal), intracranial and mediastinal locations are more difficult to explain.