You are in: eMedicine Specialties > Radiology > BRAIN/SPINE Ganglioneuroma and GanglioneuroblastomaArticle Last Updated: Mar 19, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Andrzej R Jedynak, MD, Staff Physician, Department of Radiology, UMDNJ-University Hospital Andrzej R Jedynak is a member of the following medical societies: American College of Radiology and Radiological Society of North America Coauthor(s): Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School; Yaron Lebovitz, MD, Assistant Professor of Radiology, University of Medicine and Dentistry of New Jersey; Consulting Staff, Department of Radiology, Section of Neuroradiology, University Hospital Editors: Lucien M Levy, MD, PhD, Director of Neuroradiology, Professor of Radiology, Department of Radiology, George Washington University Medical Center; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; C Douglas Phillips, MD, Professor, Departments of Radiology, Neurosurgery, and Otolaryngology, University of Virginia Health Sciences Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; L Gill Naul, MD, Professor and Head, Department of Radiology, Texas A&M University College of Medicine; Chair, Department of Radiology, Chief, Section of Magnetic Resonance Imaging, Scott and White Memorial Hospital and Clinic Author and Editor Disclosure Synonyms and related keywords: GN, GNB, neurogenic tumors, neuroblastoma, neuroblastic tumors, schwannoma, malignant schwannoma, pheochromocytoma, neuroblastoma, neurogenic cyst, neurilemoma, neurofibroma, neurogenic neoplasm, von Recklinghausen disease, neurofibromatosis, paraganglionoma, peripheral neuroectodermal tumors, PNET, sympathetic nervous system tumors, SNS tumors, pepper syndrome, blueberry muffin syndrome INTRODUCTIONSection 2 of 11
  BackgroundGanglioneuromas and ganglioneuroblastomas are tumors of the sympathetic nervous system that originate from neural crest sympathogonia, which are completely undifferentiated cells of the sympathetic nervous system. Along with neuroblastomas, ganglioneuromas and ganglioneuroblastomas are collectively known as neuroblastic or neurogenic tumors.1 Most frequently occurring in the abdomen, these tumors can grow wherever sympathetic nervous tissue is found. Common locations for ganglioneuromas and ganglioneuroblastomas include the adrenal gland, paraspinal retroperitoneum (sympathetic ganglia), posterior mediastinum, head, and neck; it is uncommon to find them in the urinary bladder, bowel wall, abdominal wall, and gallbladder. PathophysiologyGanglioneuromas, ganglioneuroblastomas, and neuroblastomas are histologically differentiated by their stage of neuroblast maturation.2 Ganglioneuromas are composed of mature ganglion cells and are considered benign tumors. Ganglioneuroblastomas and neuroblastomas are less mature and are considered more aggressive and dangerous. These tumors have a higher neuroblast content and tend to occur in young children (median age: 2 years). Composite neuroblastic tumors have been described as well; these tumors may have malignant nerve-sheath or pheochromocytoma tumors growing within them. In rare cases, von Recklinghausen disease, Beckwith-Wiedemann syndrome, Hirschsprung disease, central failure of ventilation, and DiGeorge syndrome have been associated with ganglioneuroma and ganglioneuroblastoma.3 In general, neuroblastic or neurogenic tumors appear radiologically as well-circumscribed, smooth or lobulated masses that may contain calcifications. The benign (ganglioneuromas) and malignant (ganglioneuroblastomas) forms of these tumors are virtually identical radiologically. The only differentiating factor is the possibility of distant metastases with malignant ganglioneuroblastomas. In the mid-1980s, the International Neuroblastoma Staging System (INSS) was developed to stage these tumors by using clinical, radiologic, and surgical data (see the eMedicine article Neuroblastoma in the Pediatrics section for more information on the INSS).3 Ganglioneuromas Ganglioneuromas are rare, benign, fully differentiated tumors that contain mature Schwann cells, ganglion cells, fibrous tissue, and nerve fibers. These tumors have no immature elements (such as neuroblasts), atypia, mitotic figures, intermediate cells, or necrosis. The presence of any these tissue characteristics excludes the diagnosis of ganglioneuroma.4 Ganglioneuromas can grow almost anywhere along the paravertebral sympathetic ganglia, and they can sometimes grow in the adrenal medulla.5 Overall, patients with ganglioneuroma have a favorable prognosis. Ganglioneuroblastomas Ganglioneuroblastomas are a mix of malignant neuroblastoma and benign ganglioneuroma tissues; they are sometimes called transitional tumors. These lesions also originate from sympathetic cells. Histologically, they are considered malignant because they contain primitive neuroblasts along with mature ganglion cells.1 Ganglioneuroblastomas have a propensity for secreting catecholamines; approximately 90-95% actively secrete vanillylmandelic acid (VMA) and homovanillic acid (HVA). Catecholamine toxicity rarely results.3 HVA tends to be secreted by more mature and differentiated tumors, whereas VMA is usually a product of less differentiated tumors. In fact, the ratio of VMA to HVA secreted can be used as a prognostic factor to assess tumor maturity. In addition, more mature tumors may contain vasoactive intestinal peptide (VIP)–producing ganglion cells. Elevated levels of VIP can produce diarrhea, hypokalemia, and acidosis. Despite these possible comorbidities, the prognosis for patients with ganglioneuroblastomas is relatively good. These tumors may spontaneously regress or mature. Maturation occurs at an unknown rate that eventually stops at the ganglioneuroma stage. In fact, all ganglioneuromas are thought to have once been, at an earlier stage of their development, ganglioneuroblastomas or neuroblastomas.2 Regression occurs in 1-2% of tumors; the cause of ganglioneuroblastoma regression is unknown. FrequencyUnited StatesThe posterior mediastinum is the most frequent site of occurrence (38% of cases), followed by the retroperitoneum.7 Roughly 20% of these tumors occur in the adrenal medulla, and cervical lesions account for only 10% of cases. Uncommon locations, such as heart, bone, and intestines, have also been described.3 Tumors located in the central nervous system are rare. Ganglioneuroblastoma tumors are usually found in the adrenal medulla (35%), retroperitoneum (30-35%), posterior mediastinum (20%), neck (1-5%), and pelvis (2-3%). Other locations, such as the thymus, lung, kidney, anterior mediastinum, stomach, and cauda equina, are affected less frequently and are considered unusual. Approximately 1% of these tumors metastasize. Mortality/MorbidityPatients with low-risk or intermediate-risk tumors have a relatively good prognosis. Children with INSS stage 1, 2, and 4S tumors have a 3-year event-free survival rate of 75-90%. Children younger than age 1 year with stage 3 tumors have a 1-year event-free survival rate of 80-90%, and children younger than age 1 year with stage 4 tumors have a 1-year event-free survival rate of 60-75%. Children older than age 1 year with INSS stage 3 tumors have a 3-year event-free survival rate of 50%, and children older than age 1 year with INSS stage 4 tumors have a 3-year event-free survival rate of 15%.8
SexGanglioneuromas occur slightly more often in girls than in boys, with a female-to-male ratio of about 1.5:1.3 Ganglioneuroblastomas occur with equal frequency in boys and girls.1 AgeNeuroblastic tumors account for approximately 15% of neoplasms in children younger than age 4 years, and more than 90% of cases are diagnosed before the patient is aged 5 years. These statistics make neuroblastic tumors the most common solid neoplasm in children occurring outside the central nervous system.
AnatomyGross anatomic features The gross appearance of neurogenic tumors varies greatly as a result of several factors, such as the number of ganglion cells and the degree of differentiation.1 In general, these neoplasms are rarely larger than 10 cm in diameter, and they can be either well-circumscribed or infiltrative; neoplasms occurring in the adrenal medulla and posterior mediastinum tend to be well-circumscribed. Although neuroblastic tumors are generally not encapsulated, they do appear to have a capsule. Ganglioneuroma and ganglioneuroblastoma specimens feel firm to the touch, and they can be either smooth or lobulated. The cut surface may be hemorrhagic (neuroblastic tissue), tan (stroma), or necrotic. Areas of calcifications may be observed.3 Histologic features The primary histologic features of these tumors are neuroblasts (immature, undifferentiated sympathetic cells), ganglion cells (mature cells), Schwann cells, and stroma (tissue surrounding the ganglion cells). Secondary histologic features include necrosis, mitosis, hemorrhage, fibrosis, calcification, lymphocytic infiltrate, and karyorrhexis (fragmentation of cellular nuclei that usually symbolizes cell death). Ganglioneuromas are considered to be mature tumors that do not have immature elements such as neuroblasts and mitotic activity. The presence of neuroblasts automatically makes the tumor a ganglioneuroblastoma or neuroblastoma, thereby excluding the diagnosis of ganglioneuroma. Ganglioneuromas average 8 cm in size and have a pseudocapsule. They are firm to the touch and have a light color, ranging from white to yellow. Internally, the tumor may have a whorled appearance, with trabeculae. Risk groups These neoplasms are histologically classified into risk groups by using 2 distinct systems: the Shimada classification (see the eMedicine article Neuroblastoma in the Pediatrics section for a discussion of the Shimada classification system) and the Pediatric Oncology Group (POG) classification.9 These systems are not meant for staging the disease; instead, they use histologic features to assess the prognosis of a specific tumor. The POG classification system uses only the histologic differentiation of the tumor components to assess the prognosis. Ganglioneuroma, for example, has completely mature and differentiated cells and stroma; therefore, patients with ganglioneuroma have a good prognosis. Ganglioneuroblastoma, on the other hand, is composed of both mature ganglion cells and immature neuroblasts; therefore, it is considered to have an intermediate potential for malignancy. The Shimada classification considers patient age in addition to the histologic appearance in the stratification of a tumor. Histologic features taken into consideration are stromal components (stroma-rich tumors are more mature than stroma-poor tumors), grade, cellular differentiation, and nuclear morphology. Each of these categories is further divided into multiple subcategories. The tumors are eventually classified as having either favorable or unfavorable histologic characteristics. Favorable histologic characteristics are usually found in patients younger than age 1.5 years with a low-to-intermediate mitosis-karyorrhexis index (MKI) and a differentiating or partially differentiating tumor, and in patients aged 1.5–5 years with a low MKI and a differentiating tumor. All remaining combinations are classified as unfavorable histologic characteristics.10 "The mitosis-karyorrhexis index (MKI) is defined as the number of tumor cells in mitosis and in the process of karyorrhexis. Mitotic figures are characterized by more or less rod-shaped condensations of chromatin, with spiked projections and the absence of a nuclear membrane. Karyorrhectic cells show condensed and fragmented nuclear material usually accompanied by condensed eosinophilic cytoplasm."2 Clinical DetailsGanglioneuromas Ganglioneuromas are usually asymptomatic, regardless of their size, and they are typically discovered on a routine radiograph; however, abdominal pain, dyspnea, cough, and palpation of an abdominal mass may be clinical indicators of a ganglioneuroma. These tumors may be hormonally active, and hypertension, diarrhea, flushing, and virilization may occur as a result the secretion of catecholamine, vasoactive intestinal polypeptide, or androgenic hormone. Nonetheless, emergency situations caused by catecholamine secretion are rare.
Patients with ganglioneuroblastomas often present with pain caused by either the primary tumor or by metastatic disease and abdominal distention. Patients may also complain of irritability, weight loss, malaise, shortness of breath, peripheral neurologic symptoms (nerve or nerve root compression), and Horner syndrome (ptosis, myosis, and ipsilateral anhydrosis).3 When ganglioneuromas and ganglioneuroblastomas metastasize, bone is the most common site of metastatic spread. Up to 60% of ganglioneuroblastoma/neuroblastoma patients have bone metastasis at the time of presentation. Bone metastasis accompanied by limping and irritability is called Hutchinson syndrome. Bone metastases occur in 2 patterns: diffuse (cortical, with a poor prognosis and a poor response to chemotherapy) and nodular (prognostically more favorable disease of the bone marrow). Another organ that may harbor metastatic tumors is the liver. Liver metastases can also have diffuse or nodular patterns. Pepper syndrome is the presence of large liver metastases in infants. Intra-abdominal pressure may reach such high values in these patients that abdominal surgery may be required to relieve it. In children younger than 1 year, skin metastases are common. These metastases occur as darkly pigmented masses resembling blueberries (called "blueberry muffin syndrome"). The lung, dura, and brain are considered unusual locations for metastases.3 Screening Screening infants for ganglioneuroblastoma by using vanillylmandelic acid (VMA) and homovanillic acid (HVA) levels in urine has been investigated. The results indicate that screening usually can detect small, low-grade, and histologically favorable tumors. These tumors most likely regress, mature, or remain undiscovered. In addition, infant screening has no affect on the incidence of higher-grade, more malignant tumors in older children. One study showed no effect on the outcomes of aggressive tumors discovered in infants with screening.11 Preferred ExaminationMagnetic resonance imaging (MRI) and computed tomography (CT) scanning are the preferred methods for imaging ganglioneuromas and ganglioneuroblastomas. MRI is the modality of choice for evaluating the extension of spinal tumors.3 CT scanning is the imaging modality that is most commonly used to evaluate neuroblastic tumors. It has proven to be the superior imaging technique when identifying tumor size, organ of origin, tissue invasion, vascular encasement, adenopathy, and calcifications. Newly diagnosed cases are evaluated with standard chest, abdominal, and pelvic CT scans.3 DIFFERENTIALSSection 3 of 11
Adrenal Adenoma Adrenal Carcinoma Neuroblastoma Pheochromocytoma Other Problems to Be ConsideredNeurofibroma
RADIOGRAPHSection 4 of 11
FindingsOn radiologic examination, all neuroblastic tumors (ie, ganglioneuroblastomas, ganglioneuromas, and neuroblastomas) look similar. The main difference is that ganglioneuroblastomas and neuroblastomas can possibility metastasize. These tumors have highly variable radiologic appearances and growth behaviors that are reflective of their variable locations. Conventional radiographs show a retroperitoneal, posterior mediastinal, pelvis, or neck mass. Up to 30% of these tumors may show calcifications. Rib and vertebral foraminal erosions, increased intercostal spaces, and vertebral body pedicle erosions may be seen with both retroperitoneal and posterior mediastinal tumors. Hepatomegaly, periostitis, widened cranial sutures, focal bone lucencies, focal bone sclerosis, and lucent submetaphyseal zones may indicate metastatic disease.3 CT SCANSection 5 of 11
FindingsCT scanning is the imaging modality that is most commonly used to evaluate neuroblastic tumors. It has proven to be the superior imaging technique when identifying tumor size, organ of origin, tissue invasion, vascular encasement, adenopathy, and calcifications. Newly diagnosed cases are evaluated with standard chest, abdominal, and pelvic CT scans.3 Ganglioneuromas Retroperitoneal and adrenal ganglioneuromas appear well-defined. Their shape ranges from round to lobulated, they show discrete and punctate calcifications in 42-60% of cases, and they tend to grow around major blood vessels. The tumors do not compress these blood vessels, and blood flow remains normal.1 Nonenhanced CT scanning reveals a homogeneous mass with less attenuation than muscle. Ichikawa et al described a delayed heterogeneous uptake of contrast in a ganglioneuroma.12 The reason for this type of uptake is that these tumors take longer to accumulate contrast material in the extracellular space. This delay is directly proportional to the amount of myxoid stroma in the tumor. Ganglioneuroblastomas Ganglioneuroblastomas have a variable appearance on CT and can be cystic or solid.1 Abdominal and pelvic tumors are mostly heterogeneous and large; smaller tumors may appear homogeneous. Areas of bleeding and necrosis may be as large as 4 cm and appear to be of lower attenuation. These tumors can grow around blood vessels but rarely invade them. Vessel compression, however, is a realistic possibility. If compression of renal vasculature occurs, hypertension can result.3 Other vessels at risk include the splenic vein, inferior vena cava, aorta, celiac artery, and superior mesenteric artery (SMA). Any metastasis to the liver or lung and adenopathy can also be identified on CT. Liver metastases appear as diffuse infiltration (in infants) and as focal areas of low enhancement. Metastatic disease of the lung can appear either as well-defined nodules or as larger areas of tissue consolidation. Although exceedingly rare, brain metastases do occur and have a variable appearance, ranging from hemorrhagic to cystic with rim-enhancement to a solid mass. Intracranial dural involvement is a more common occurrence and can be seen as meningeal masses and meningeal enhancement. These metastatic tumors may be large enough to produce mass effect on the brain and cranium (suture widening). Metastatic involvement of the sphenoid bone that extends into the orbits produces a red and blue discoloration of the orbits that can be misinterpreted as physical abuse.13 MRISection 6 of 11
FindingsMRI is a multiplanar imaging technique that creates images with better tissue discrimination than CT. This makes MRI more effective at evaluating organs of origin, regional invasion, and intraspinal tumoral extension. Any patient with a paraspinal tumor should undergo an MRI to evaluate possible tumoral invasion of the epidural space. In these cases, coronal, sagittal, and axial views can demonstrate spinal cord and nerve root displacement as well as superior and inferior tumor growth. MRI is also useful for imaging bone marrow; the lesions appear hypointense on T1-weighted images and hyperintense on T2-weighted images. Lastly, MRI can be used to detect hepatic metastases in infants with stage 4S disease, which can be missed on CT scanning because of its appearance as a uniform increase in liver attenuation. These lesions appear hyperintense on T2-weighted MRIs.3 Ganglioneuromas Ganglioneuromas appear homogeneous on MRIs and have a relatively intermediate signal intensity on all sequences.14 Tumors with intermediate-to-high signal-intensity on T2-weighted images have a higher degree of cellularity and more collagen. These tumors will have a small myxoid component. Markedly-high T2 intensity, on the other hand, signifies a high myxoid stroma component and low cellularity and collagen amounts.1 Ganglioneuromas have characteristic curvilinear bands of low signal-intensity on T2-weighted images that impart a whorled pattern to the tumor. These bands are composed of collagen fibers and intertwined bundles of Schwann cells. The capsule surrounding the tumor appears as a low-density ring on both T1- and T2-weighted images. Contrast enhancement with MRI is similar to contract enhancement with CT imaging. Early contrast enhancement occurs in areas of relatively high vascularity with high capillary permeability. Delayed enhancement, on the other hand, results when diffusion of the enhancing material into the extravascular space is slowed or impeded.15 Therefore, fibrous tissues show slow or late enhancement. These tumors enhance gradually, with final enhancement ranging from none to marked. MRI is the modality of choice for evaluating the extension of spinal tumors.3 Ganglioneuroblastomas Ganglioneuroblastomas appear heterogeneous on MRIs, with variable enhancement and low signal-intensity on T1-weighted images and high signal-intensity on T2-weighted images.16 Tumor calcifications are more difficult to appreciate on MRIs than on CT scans; on MRIs, they appear as signal voids. Areas of hemorrhage have a high T1 signal-intensity and cystic areas have a high T2 signal-intensity.3 Ganglioneuroblastomas, like neuroblastomas and other malignant tumors, have an enhancing pattern of early enhancement followed by a partial washout; early enhancement is indicative of high vascularity.15 False Positives/NegativesThe differential diagnosis of ganglioneuroma and ganglioneuroblastoma includes neuroblastoma, adrenal adenoma, adrenal carcinoma, neurofibroma, schwannoma, and pheochromocytoma. Ganglioneuromas can be differentiated from more aggressive neuroblastomas and ganglioneuroblastomas by their regular contours and lack of tissue invasion and vessel encasing, their occurrence in older patients, and their discrete, punctate calcifications on CT scans. Neuroblastomas and ganglioneuroblastomas tend to have amorphous or coarse calcifications. In addition, ganglioneuromas rarely metastasize, whereas neuroblastomas and ganglioneuroblastomas can metastasize to bone, skin, and other organs.15 It is more difficult to differentiate ganglioneuromas from schwannomas or neurofibromas. In general, schwannomas and neurofibromas are round and can cause bone erosion and destruction. Most ganglioneuromas are flat and elongated and they normally do not affect bone. Schwannomas may demonstrate cystic degeneration that does not occur in ganglioneuromas. Neurofibromas do not have a capsule; the presence of one in a patient would point to a ganglioneuroma diagnosis.15 Adrenal disease can be differentiated from neuroblastic tumors by its unique enhancing patterns. Adrenal adenomas enhance and wash out early, whereas pheochromocytomas and adrenocortical carcinomas strongly enhance early but wash out at a slower rate. Adrenal carcinomas invade vascular structures in more than 50% of the cases.15 ULTRASOUNDSection 7 of 11
FindingsGanglioneuromas Ultrasonography of a ganglioneuroma would show a homogeneous, hypoechoic, well-circumscribed mass. Ganglioneuroblastomas Ganglioneuroblastomas show heterogeneic echogenicity, with areas of hemorrhage and necrosis appearing anechogeneic. Calcifications appear as either focal or diffuse areas of increased echogenicity with variable appearance of shadowing. Ultrasonography has proven to be useful in evaluating other organs for metastasis, and for determining blood flow in blood vessels surrounded by tumor.3 NUCLEAR MEDICINESection 8 of 11
FindingsIn cases of ganglioneuroblastoma, scintigraphy is not only useful for identifying the primary tumor, but it is also useful for monitoring the pattern of metastatic spread. Primary and metastatic tumors take up catecholamine and somatostatin analogs. Iodine-tagged metaiodobenzylguanidine (MIBG), a catecholamine analog, is used to identify catecholamine-producing tumors such as ganglioneuroblastoma, ganglioneuroma, neuroblastoma, pheochromocytoma, carcinoid tumor, and medullary thyroid cancer. Technetium-99m testing is an initial study done in all patients with diagnosed ganglioneuroblastoma. This test is conducted to determine the amount of metastatic disease present; however, as many as 75% of primary tumors also show uptake. This method is preferred for the examination of bone metastases as cortical and marrow lesions are difficult to discriminate (as they are with MIBG studies). Metastases appear as areas of higher uptake, and they include areas such as the lung and liver. The amount of technetium-99m uptake is, purportedly, directly related to calcium metabolism of the tumor cells. Ganglioneuromas can accumulate MIBG in a fashion similar to ganglioneuroblastomas; tumors that uptake MIBG are catecholamine-producing tumors. Degree of ConfidenceAlthough 90-95% of ganglioneuroblastomas produce catecholamines, only approximately 70% take up MIBG. Therefore, negative results do not mean there is no disease. Despite this limitation, MIBG scintigraphy has an 88% sensitivity and a 99% specificity for tumors containing sympathetic tissue, such as ganglioneuroblastomas, ganglioneuromas, neuroblastomas, pheochromocytomas, and carcinoids. The disadvantage is that there is no way to discriminate the type of tumor in which the uptake occurs. When bone is affected, this method also makes staging difficult, because it does not distinguish cortical involvement from marrow involvement. Unfortunately, up to 50% of recurrent tumors do not take up MIBG. This makes MIBG scintigraphy a poor method of post-therapeutic monitoring for recurrences. Somatostatin-analog testing is also used to evaluate neuroblastic tumors, but it is not as specific as an MIBG study.3 INTERVENTIONSection 9 of 11
Ganglioneuromas are staged by using the INSS. Treatment is usually in the form of surgical excision if tumors are localized and show no distant metastasis.3 Complete surgical resection is important because it allows for good tissue sampling and a thorough pathology examination of the specimen to ensure a correct diagnosis of ganglioneuroma. In rare cases, these tumors recur; therefore, radiologic examination is an important tool for the proper localization and characterization of primary and recurrent tumors. These tumors are identified on radiologic examination on the basis of their location, shape, and internal structure; however, the diagnosis of ganglioneuroma cannot be based on radiologic findings alone. Patients have an excellent prognosis after surgical resection. Low-risk tumors are usually treated with surgical resection only. Intermediate-risk tumor patients may need chemotherapy after surgery. The tumor should be resected as completely as possible, because this may have an influence on the prognosis of higher-stage disease. The time of resection seems to have no effect on the prognosis. Patients with high-risk tumors have a less favorable prognosis. These tumors tend to be large, aggressive, and difficult to resect. Treatment with chemotherapy before surgery may be indicated in order to make the tumor smaller and more resectable. In some cases, surgery, chemotherapy, and bone marrow transplantation may be necessary. Even with these efforts, a 3-year survival rate of less than 15% has been reported in cases of advanced disease. Advanced tumors (stage 4) or metastatic disease may benefit more from chemotherapy because surgery has not been shown to increase survival rates. Surgery should be used palliatively to minimize, rather than completely excise, these high-stage tumors. MULTIMEDIASection 10 of 11
REFERENCESSection 11 of 11
Ganglioneuroma and Ganglioneuroblastoma excerpt Article Last Updated: Mar 19, 2008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
