Adrenal Masses in Infancy and Childhood; A Clinical and Radiological Overview

Adrenal masses derive from the medulla in most cases and rarely from the cortex. Neoplastic medullary tumors often originate from primitive neural crest cells such as neurogenic tumors including neuroblastoma, ganglioneuroblastoma and ganglioneurinoma. The adrenal medulla is the most common site of neuroblastoma, namely 35%. These tumors are composed of undifferentiated cells, while ganglioneuroma are composed entirely of mature ganglion and schwancells. Ganglioneuroblastoma include both mature and immature cell types. In addition to imaging, measurement of catecholamine excretion is valuable as an initial diagnostic procedure and for evaluation of therapeutic response. Progress in imaging techniques contributed largely in diagnosis and evaluation of extension of neurogenic adrenal masses, especially in staging of such tumors. Sonography is the first modality of choice in evaluation of neurogenic adrenal tumors and may help to delineate the tumor from adjacent organs such as the kidney and is useful in evaluation of other involved organs. Sonographically these tumors are usually heterogeneously echogenic with signs of necrosis or hemorrhage with or without calcification. The use of MIBG scintigraphy (Meta-IodinBenzylGuanidine) is absolutely indicated in diagnosis of neurogenic adrenal masses, staging and evaluation of therapeutic response. CT is the most commonly used modality for assessment of neurogenic tumors and is superior to sonography in the evaluation of tumor extension and metastatic disease. MRI is an adequate modality in the evaluation of masses with extension to the spinal channel. MR imaging of neuroblastoma usually shows a low T1, a high T2, and heterogeneous enhancement. However, the detection of calcification (30%) may be difficult. Pheochromocytoma is a secretory tumor arising from neuro-ectodermal chromaffin cells in the medulla of adrenal glands (70%) or in extra-adrenal sites. The clinical presentation is usually related to the secretion of catecholamine with clinical symptoms such as hypertension, sweating, headaches, blurred vision, flushing and tachycardia. Accurate diagnostic imaging is required for a successful surgical management of pheochromocytoma. In such cases sonography should be used only as an initial procedure and because of its often multifocal location added with other modalities such as CT and/or MRI and functional imaging with MIBG. Adrenocortical neoplasms such as carcinomas and adenomas are uncommon in childhood and occur in ages more than 3 years. Usually girls are more often affected than boys. Carcinomas are