Many of the tumors that are regarded as malignant in older children may behave in a more benign fashion in the fetus and neonate, including neuroblastoma, congenital myeloproliferative disorder in Trisomy 21, congenital fibrosarcoma, and hereditary retinoblastoma. A number of genetic, chromosomal, and syndromic associations are reported for fetal and neonatal tumors. Germ cell tumors comprise both benign and malignant tumors and can arise in both gonadal and extragonadal locations; the latter are usually found in the midline, including the sacrococcygeal area, mediastinum, and neck. Teratomas contain tissues derived from all three embryonic layers (viz. ectoderm, mesoderm, and endoderm) with a wide range of histological patterns. Neuroblastoma represents a classical embryonal tumor of neuronal lineage that may occur in the adrenal medulla and any other sites of sympathetic ganglia, from the neck to the presacral region.

This chapter outlines the prenatal imaging and clinical diagnoses of neonatal and pediatric tumors. It discusses the antenatal natural history, and reviews available treatment options during the pre- and postnatal period for fetuses with prenatally diagnosed tumors. The differential diagnosis of a prenatally diagnosed intracranial tumor includes teratoma, which make up the majority of lesions, hemangioma and papilloma. Prenatal ultrasonography and fetal MRI are useful in evaluating and determining the etiology of the intracranial tumor. The surgical approach to bronchopulmonary sequestrations (BPS) is straightforward, with a muscle sparing thoracotomy or thoracoscopic approach for chest lesions and laparotomy or laparoscopy for subdiaphragmatic BPS, with particular attention to first controlling the anomalous blood supply in all cases. The most common primary hepatic tumor is hemangioma, followed by mesenchymal hamartoma, and hepatoblastoma. The differential diagnosis of mesoblastic nephroma includes hydronephrosis and multicystic dysplastic kidney, focal renal dysplasia, and diffuse nephroblastomatosis and nephroblastoma.