Malignant germ cell tumors (GCTs) and gonadal tumors are rare, with an incidence of 12 cases per million persons <20 yr of age. Most malignant tumors of the gonads in children are GCTs. The incidence varies according to age and sex.
Sacrococcygeal tumors occur predominantly in infant girls.
Testicular GCTs occur predominantly before age 4 yr and after puberty. Testicular GCTs occur much more often in whites than in blacks, whereas ovarian GCTs have a slight predominance in blacks.
Klinefelter syndrome is associated with an increased risk of mediastinal GCTs;
Down syndrome, undescended testes, infertility, testicular atrophy and inguinal hernias are associated with an increased risk of testicular cancer.
The serum ?-fetoprotein (AFP) level is elevated with endodermal sinus tumors and may be minimally elevated with teratomas. Infants have higher levels of AFP, which fall to normal adult levels by about 8 mo; therefore, high AFP levels must be interpreted with caution in this age group. Elevation of the ? subunit of human chorionic gonadotropin (?-hCG) is seen with