Mediastinal Neuroblastoma

Axial CT image at the level of mid thoracic spine of a 5-year-old boy shows a well-circumscribed, enhancing left paraspinal mass located between the medial ends of the ribs. 

An MIBG study (posterior view of the thorax and upper abdomen) shows a focus of moderate uptake in the left side of the lower thorax, corresponding with the site of abnormal mass on CT. Note intense uptake of bilateral adrenal glands. 

Facts: Neuroblastoma

• 8-10% of all childhood malignancies
• Malignant tumor composed of immature ganglion cells. Most (2/3) arise from abdomen or pelvis and the rest is extra abdominal
• Typically seen in children under age of 5 years
• Treatment determined by stage of tumor at presentation. Regionally limited disease is potentially resectable, but locally extensive or disseminated disease is usually not resectable
• Current imaging staging evaluation: 1) CT or MRI of primary tumor, 2) skeletal survey, 3) bone scintigraphy or MIBG for bone metastasis, and 4) bone marrow aspiration and biopsy for marrow disease
• CT alone has low sensitivity (43%) but high specificity (97%) for detection of stage 4 disease. CT accuracy = 81%. MRI is more sensitive (83%) but less specific (88%) and slightly more accurate (85%). 

Imaging Findings: CT/MRI

• Sharply marginated, fusiform paraspinal mass
• Oriented along direction of sympathetic chain
• 40% contain calcifications
• Heterogeneous enhancement
• Differentiation from ganglioneuroblastoma (usually 5-10 years old) and ganglioneuroma (usually > 10 years old) not possible by imaging. Basically, they are tumors of sympathetic ganglia

References
1. Siegel MJ. Pediatric Body CT. 2008
2. Siegel MJ, Ishwaran H, Fletcher BD, et al. Staging of neuroblastoma at imaging: report of the radiology diagnostic oncology group. Radiology 2002;223:168-175.