Right adrenal neuroblastoma in a 5-yearold girl. Contrast-enhanced CT scan shows a lobulated, inhomogeneous mass with low attenuation that is located in the right suprarenal region and extends across the midline. Dense intratumoral calcifications are also noted (arrows). The tumor displaces the aorta (A) and inferior vena cava (V ) ventrally.

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Context 1

... contain calcification in approximately 85% of cases at CT and in up to 55% of cases at con- ventional radiography (19). Calcifications in neu- roblastomas are usually coarse, amorphous, and mottled in appearance (Fig 5), as opposed to the discrete and punctate calcifications observed in ganglioneuromas. CT and MR imaging are useful for defining the morphologic features of neuro- blastoma and precisely assessing tumor extent. ...

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... gross examination, ganglioneuroblastomas may be partially or totally encapsulated and frequently contain granular calci fi cation (15). Their appearance varies depending on the number of ganglion cells, their degree of differentiation, and their relationship to immature elements (3). Therefore, the reported CT fi ndings in ganglioneuroblastomas also vary, ranging from a predominantly solid mass to a predominantly cystic mass with a few thin strands of solid tissue (15 – 17). Neuroblastomas are malignant tumors that consist of primitive neuroblasts and may arise anywhere within the sympathetic plexus or adrenal medulla (15). At histologic analysis, neuroblastomas are composed of small, dark neuroepi- thelial cells that may show glial or ganglionic differentiation and contain nests of primitive round cells with dark-staining nuclei and scant cyto- plasm. They most commonly occur during the fi rst 10 years of life. Boys are more frequently affected than girls. Approximately 80% of these neoplasms are found in children under the age of 5 years, and 35% are found in those under the age of 2 years (15). Two-thirds of neuroblastomas are located in the abdomen, and approximately two- thirds of these abdominal lesions arise in the adrenal gland. The remaining abdominal or pelvic tumors almost always originate in the paravertebral sympathetic chain or presacral area, with an occasional abdominal tumor arising in the celiac axis or organ of Zuckerkandl. Adult-type abdominal neuroblastomas have been reported only very rarely (18). Neuroblastomas tend to metastasize to bone, bone marrow, liver, lymph nodes, and skin. At least 70% of affected patients have dis- seminated disease at the time of diagnosis (15). Neuroblastomas are more aggressive than ganglioneuromas; the majority are irregularly shaped, lobulated, and unencapsulated. Sometimes they invade adjacent organs or encase adjacent vessels. Neuroblastomas tend to be inhomogeneous ow- ing to tumor necrosis and hemorrhage (Fig 4). They contain calci fi cation in approximately 85% of cases at CT and in up to 55% of cases at con- ventional radiography (19). Calci fi cations in neuroblastomas are usually coarse, amorphous, and mottled in appearance (Fig 5), as opposed to the discrete and punctate calci fi cations observed in ganglioneuromas. CT and MR imaging are useful for de fi ning the morphologic features of neuroblastoma and precisely assessing tumor extent. They can also help determine tumor extension to the retroperitoneal lymph nodes and liver, around the central vessels, and into the vertebral canal (15). The paraganglia are widely dispersed collections of specialized neural crest cells that lie adjacent to the sympathetic ganglia and plexuses throughout the body. The paraganglionic system includes the adrenal medulla, the chemoreceptors (ie, carotid and aortic bodies), vagal body, and the small groups of cells associated with the thoracic as well as intraabdominal and retroperitoneal ganglia (3). Tumors that arise from the chromaf fi n cells of the adrenal medulla are called pheochromocytomas, whereas those that occur in paraganglia at other sites are referred to as paragangliomas. Although their true prevalence is unknown, pheochromocytomas are thought to be the cause of hypertension in approximately 0.1% – 0.5% of patients with newly diagnosed hypertension. These tumors occur with equal frequency in men and women and appear to be more common in the 3rd and 4th decades of life (20). Pheochromocytomas have been called “ ten percent tumors ” because approximately 10% are bilateral, 10% are extraadrenal (paragangliomas of the retroperitoneum, mediastinum, or urinary bladder), 10% occur in children, and 10% are malignant. When they occur in children, there often tends to be a high familial prevalence. Pheochromocytomas are associated with multiple endocrine neoplasm (MEN) IIa and IIb or III syndrome, von Hippel – Lindau syndrome, and neuro fi bromatosis type 1 (NF-1, von Recklinghausen disease, or peripheral neuro fi bromatosis). MEN IIa syndrome consists of pheochromocytoma, medullary carcinoma of the thyroid gland, and parathyroid hyperplasia, whereas MEN IIb or III syndrome consists of pheochromocytoma, medullary carcinoma of the thyroid gland, ganglioneu- romatosis, and multiple mucosal neuromas (20). Pheochromocytomas associated with MEN syn- drome tend to be bilateral and are almost always intraadrenal; they also tend to be benign (21). The clinical manifestations of pheochromocytoma result from the known physiologic effects of catecholamine release. The classic triad of head- ache, palpitation, and excessive sweating is seen during the paroxysmal hypertensive crisis. Uri- nary metanephrine or vanillylmandelic acid levels are elevated in over 90% of patients from whom 24-hour urine collections are obtained (21). If laboratory test results indicate a pheochromocytoma, CT of the adrenal gland is performed fi rst. If no lesion is found, CT is then performed through the organ of Zuckerkandl to encompass all chromaf fi n cell-bearing tissue along the lower abdominal aorta from the origin of the inferior mesenteric artery to the aortic bifurcation and into the iliac vessels. If there is still no evidence of a lesion, CT is performed on through the bladder, another common site of paraganglioma. At CT, both pheochromocytomas and paragangliomas are usually 3 cm or larger, demonstrate areas of necrosis or hemorrhage (Fig 6), and may even contain fl uid- fl uid levels except in patients with MEN syndrome, in whom the tumors tend to be small. In MEN syndrome, the adrenal glands can be thickened and nodular without large masses (adrenal medullary hyperplasia) (20). The tumors are hypervascular and exhibit marked enhance- ment after intravenous administration of contrast material. CT can be performed safely with intravenous administration of low-osmolarity, nonionic contrast material; recent studies have shown no elevation of serum catecholamine levels when such contrast material is used ...