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Key Points
Most common solid tumor in infants.
Neuroblastomas are generally diagnosed by sonography in the third trimester, and can be cystic, solid, or both.
The differential diagnosis includes hydronephrosis, multicystic kidney, obstructive duplex collecting system, Wilms’ tumor, mesoblastic nephroma, and adrenal hemorrhage.
Neuroblastoma in situ may be responsible for many prenatally diagnosed cystic neuroblastomas, and may be due to delayed regression of neuroblasts.
83% of prenatally diagnosed neuroblastomas will be localized stage I or II disease.
Neuroblastoma is stage III or IVS in only 16% of cases.
Poor prognostic signs, such as N-myc amplification, occur in less than 5% of cases.
Prenatal complications such as fetal hydrops, hepatomegaly, and maternal hypertension occur rarely.
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Neuroblastomas arise from undifferentiated neural tissue of the adrenal medulla (40% to 70%), or extraadrenal sympathetic ganglia (30% to 60%), in the abdomen, thorax, pelvis, or head and neck (Birner, 1961; Beckwith and Perrin, 1963; Schneider et al., 1965; Janetschek et al., 1984; Ferraro et al., 1988). Neuroblastic nodules appear to be normal fetal structures within the adrenal gland that regress or differentiate throughout gestation. Greater numbers of these nodules are present early in gestation than at birth or during early infancy (Turkel and Habashi, 1974; Ikeda et al., 1981; Grosfeld et al., 1993). Neuroblastic nodules were found in 100% of the adrenal glands studied in second trimester abortuses (Turkel and Habashi, 1974; Ikeda et al., 1981) (Figure 113-1). Postnatal autopsy studies of newborn and young infants who died of unrelated causes reveal nodules to be present in 0.5% to 2.5% of carefully sectioned specimens (Beckwith and Perrin, 1963; Guin et al., 1969; Grosfeld et al., 1993). These figures contrast with the incidence of symptomatic neuroblastoma of 1 in 10,000 to 1 in 30,000 children. This calls into question the clinical significance of these early lesions and the need for treatment. It is also of interest that adrenal cysts are more commonly seen in fetal neuroblastoma, but are relatively uncommon in postnatal life (Turkel and Habashi, 1974). Cystic change may also represent a phase of normal adrenal development, thus accounting for prenatal detection of sonographically apparent but possibly clinically insignificant tumors (Tubergen and Heyn, 1970) (Figure 113-2). Although these tumors may represent rests of neural tissue with persistence into neonatal life, the potential for malignant transformation due to defective regression or differentiation must be considered (Turkel and Habashi, 1974; Grosfeld et al., 1993). Beckwith referred to these lesions as “neuroblastoma in situ” because these aggregates of neuroblasts exhibited mitotic figures and infiltration of the adult cortex (Beckwith and Perrin, 1963).
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