What are teratomas?

May be benign well-differentaied cystic lesions (mature), indeterminate potential (immature) or malignant (other germ cell tumor) two peaks (first at 2 years, second in late adolescence slow growing prenatal) Most common in childhood is sacrococcygeal teratoma(40%) 4 times more common in girls, 10% of teratomas are congenital anomalies (hindgut/cloacal region anomaly) 75% mature, 12% malignant and lethal, remainder is immature have malignant potential neuroepithelial elements present, most are encountered at younger infants (<4months) malignants at much older, other sites are testis, ovaries, midline locations (mediastinum, retroperitoneum, head and neck)