Chapter 447

Tumors are a rare but important cause of mortality and morbidity in the newborn. The types of tumors that occur at this age are substantially different from those that occur in older children. Neonatal tumors include a wide spectrum of benign and malignant tumors, some of which have unique biologic characteristics and clinical presentations. Tumor behavior is not always predictable and apparently benign tumors may have a malignant potential, whereas others, malignant by histologic criteria, behave in a benign fashion in the neonate.1

The incidence of neonatal tumors varies from 17 to 121 per million live births.2-4 An apparent increase in the incidence of neonatal cancer may be due, at least in part, to the prenatal detection by ultrasound of tumors, such as neuroblastoma, that may never present clinically. Newborn cancer makes up about 2% of malignancies in children.1 Tumors presenting after birth tend to be detected early, 50% on the first day of life and many others within the first 7 days.5,6 Fifteen to 20% are associated with congenital anomalies and syndromes.1

Neonatal tumors differ in distribution from those found in older children. Table 447-1 shows the distribution of newborn tumors from a large published series.7 Overall, teratoma is the most common neoplasm, whereas neuroblastoma is the most common malignancy in newborns and infants in Western countries,8,9 followed by leukemia, sarcoma, and brain tumors. By comparison, acute leukemia is the most common cancer in newborns in a report from Asia.9

Table 447-1. Spectrum of Newborn Tumors

### Neonatal Germ Cell Tumors

Germ cell tumors consist of a heterogeneous group of histologically benign and malignant tumors which arise from primordial germ cells. All subtypes can be seen in the neonate, although mature (benign) teratoma is the most common with a reported incidence of 1 in 35,000 live births.10

Mature (benign) teratoma is the most common germ cell tumor in the newborn, comprising 37% to 52% of congenital tumors.11 Malignant elements, usually endodermal sinus tumor (EST) are found in approximately 10% of teratomas in children under age 4 months,12 but neither the degree of histologic immaturity nor the presence of malignant elements has correlated with recurrence or progression to malignancy.11 After age 4 months the malignancy rate of teratomas rises, reaching almost 100% at age 3 years.12 Mature teratomas are usually extragonadal and midline, consistent with embryonic patterns of ...

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