This is the most common tumor found in newborns, with an incidence of 1:35,000. It is thought to occur when the primitive streak does not completely degenerate, leaving remnants of undifferentiated stem cells. They are characterized by a wide variety of tissue types and all three germ layers. The prognosis is good if they are surgically removed but the possibility of malignancy increases from 10% at birth to 50-70% at 2 months. For unknown reasons, 75% of these tumors occur in females.

Adopted from Moore & Persaud, The Developing Human: Clinically Oriented Embryology. 6th edition. W.B. Saunders Company, Philadelphia, 1998.

Return to gastrulation

return to Anomalies