Joseph Junewick, MD FACR
over 7 years ago
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Joseph Junewick, MD FACR
|Diagnostic Category: Neoplasia Malignant
|Created: over 6 years ago
|Updated: over 5 years ago
15 month old with anemia.
CT – Prominent left adrenal gland with large circumscribed mixed attenuation left upper quadrant mass.
NM – Anterior and posterior whole body I-123 MIBG images after resection of abdominal disease show extensive marrow involvement.
Neuroblastic tumors derive from primordial neural crest cells destined for sympathetic differentiation. The most common sites of origin, in order, are the adrenal medulla (35% of cases), extraadrenal retroperitoneum (30%–35%), and posterior mediastinum (20%). Less common sites are the neck (1%–5% of cases) and pelvis (2%–3%) (23). Approximately 1% of patients present with metastatic disease but no discoverable primary tumor. Unusual locations such as the thymus, lung, kidney, anterior mediastinum, stomach, and cauda equina have also been described.
MIBG is taken up by catecholamine-producing tumors (neuroblastoma, ganglioneuroblastoma, pheochromocytoma, carcinoid tumor and medullary thyroid carcinoma). Although 90%–95% of neuroblastomas secrete catecholamines, only about 70% are MIBG positive. MIBG scintigraphy is highly sensitive (88%) and specific (99%) for sympathetic tissue but does not discriminate between the catecholamine-producing tumors. Positive MIBG scans provide an excellent map of primary and metastatic disease.
CT is the most commonly used imaging modality for assessment of neuroblastic tumors, because it reveals extent of tumor, organ of origin, regional invasion, vascular encasement, adenopathy, and calcification. CT of the chest, abdomen, and pelvis is standard for all newly diagnosed cases. Abdominal and pelvic tumors are usually large and heterogeneous. Approximately 80%–90% of neuroblastomas demonstrate calcification on CT scans. Low-attenuation areas of necrosis or hemorrhage are frequently noted. Vascular encasement and compression are common, although vascular invasion is rare. Regional invasion of psoas and paraspinal musculature may occur, and invasion of the neural foramen into the epidural space is also frequent. Adenopathy of the renal hilum, porta hepatis, and retroperitoneum may be seen. Metastatic disease of the liver and lung are readily evaluated with CT. Liver metastases may be diffuse infiltration or focal hypoenhancing masses. Lung metastases may appear as discreet nodules or confluent areas of parenchymal consolidation.
Lonergan GJ, Schwab CM, Suarez ES, et al. From the Archives of the AFIP Neuroblastoma, Ganglioneuroblastoma, and Ganglioneuroma: Radiologic-Pathologic Correlation. Radiographics (2002); 22:911-934.