Neonatal Tumors: Imaging Findings and Differential Diagnosis

Tumors presenting in the neonatal period are uncommon and span several organ systems. Age, anatomic compartment, internal tissue composition, vascularity, and evidence of dissemination help narrow the differential. Ultrasound is often the first examination; MRI defines soft-tissue and central nervous system extent, while CT has a selective role when calcification, bone involvement, or urgent staging must be assessed.

Central nervous system

• Teratoma is often large and heterogeneous, with mixed cystic, fatty, and calcified components.
• A pilocytic astrocytoma may appear as a cystic mass with an enhancing mural nodule, although neonatal presentations are variable.
• Embryonal tumor with multilayered rosettes is typically hypercellular, restricts diffusion, and may disseminate through cerebrospinal fluid.
• Desmoplastic infantile ganglioglioma is usually a large superficial cystic-solid mass with dural contact and avid enhancement of the solid component.
• Choroid plexus tumors are vascular intraventricular masses and commonly present with hydrocephalus.

Head, neck, and chest

• An infantile hemangioma is a hypervascular enhancing lesion with flow-related features; a lymphatic malformation is usually multicystic, may contain fluid-fluid levels, and lacks central solid enhancement.
• Cervical teratoma should prompt a search for fat and calcification and careful assessment of airway displacement.
• Multiple cardiac rhabdomyomas raise concern for tuberous sclerosis complex and may regress over time.
• A posterior mediastinal neuroblastoma may calcify and extend through a neural foramen.
• Pleuropulmonary blastoma ranges from cystic to mixed and solid morphology; imaging alone may not reliably distinguish a purely cystic lesion from a congenital pulmonary airway malformation.

Abdomen, pelvis, and soft tissues

• Congenital mesoblastic nephroma is the most common neonatal renal tumor and is usually a solid renal mass without the typical age profile of Wilms tumor.
• Adrenal neuroblastoma may be heterogeneous, calcified, or cystic and should be distinguished from adrenal hemorrhage with serial imaging and clinical data.
• Sacrococcygeal teratoma frequently contains mixed solid, cystic, fatty, and calcified tissue; define its internal and external extent.
• Soft-tissue tumors require characterization of vascularity, fascial and neurovascular relationships, and possible bone involvement.

Reporting checklist

• Record the organ or compartment of origin, three-dimensional size, margins, and tissue composition.
• Describe diffusion, enhancement, hemorrhage, fat, calcification, necrosis, and vascular encasement.
• Assess airway, neural foramina, spinal canal, major vessels, collecting systems, and adjacent organs as applicable.
• Search for multifocal disease, lymphadenopathy, and metastatic spread using the appropriate staging pathway.
• State the leading diagnosis and focused alternatives, and explicitly note limitations requiring another modality or specialist correlation.