|Year : 2019 | Volume
| Issue : 3 | Page : 105-112
Key Imaging Appearances of Commonly Encountered Pediatric Adrenal Masses
Rama Anand1, Vikas Chaudhary1, Mahender K Narula1, Isha Gupta1, Subhasis R Choudhury2, Manjula Jain3
1 Department of Radiodiagnosis, Lady Hardinge Medical College and Associated Smt. Sucheta Kriplani & Kalawati Hospitals, New Delhi, India
2 Department of Pediatric Surgery, Lady Hardinge Medical College and Associated Smt. Sucheta Kriplani & Kalawati Hospitals, New Delhi, India
3 Department of Pathology, Lady Hardinge Medical College and Associated Smt. Sucheta Kriplani & Kalawati Hospitals, New Delhi, India
|Date of Submission||21-Jul-2019|
|Date of Decision||19-Sep-2019|
|Date of Acceptance||21-Sep-2019|
|Date of Web Publication||17-Dec-2019|
Dr. MD, Associate Professor Vikas Chaudhary
Department of Radiodiagnosis, Lady Hardinge Medical College and Associated Smt. Sucheta Kriplani & Kalawati Hospitals, New Delhi - 110001
Source of Support: None, Conflict of Interest: None
Adrenal masses in children may occur as a result of neoplasm, hemorrhage, infection, or cysts. Ultrasound is the initial imaging modality of choice in suspected adrenal pathology in children. Computed tomography, magnetic resonance imaging, and functional imaging are usually required for confirmation and further characterization of adrenal lesions. This review article highlights the imaging features of common adrenal masses that may involve the adrenal gland in pediatric population.
Keywords: Adrenal masses, children, computed tomography, magnetic resonance imaging, ultrasonography
|How to cite this article:|
Anand R, Chaudhary V, Narula MK, Gupta I, Choudhury SR, Jain M. Key Imaging Appearances of Commonly Encountered Pediatric Adrenal Masses. MAMC J Med Sci 2019;5:105-12
|How to cite this URL:|
Anand R, Chaudhary V, Narula MK, Gupta I, Choudhury SR, Jain M. Key Imaging Appearances of Commonly Encountered Pediatric Adrenal Masses. MAMC J Med Sci [serial online] 2019 [cited 2020 Jan 26];5:105-12. Available from: http://www.mamcjms.in/text.asp?2019/5/3/105/273285
| Introduction|| |
Owing to the presence of prominent fetal adrenal cortex, normal adrenal glands can be seen prenatally with ultrasound (US) and magnetic resonance imaging (MRI). However, due to physiologic atrophy of adrenal cortex, it becomes difficult to visualize adrenal glands on US beyond the late infancy, but they can be easily seen on computed tomography (CT) or MRI. Easy accessibility, lack of ionizing radiation, and availability of good acoustic window to visualize suprarenal fossa make US the primary modality of choice for imaging adrenal lesions in neonates; however, multidetector-row CT (MDCT) or MRI is usually required in older children, after initial US, for confirmation and further characterization of adrenal lesions and tumor staging. Functional imaging modalities, such as positron emission tomography (PET) and single-photon emission CT (SPECT), can be used for evaluation of primary adrenal lesion, residual/recurrent disease, and metastases in children. Radionuclide studies like 123I-labeled metaiodobenzylguanidine (123I-MIBG) or technetium-99m (99mTc) scintigraphy may be used to establish initial diagnosis, search for distant metastases, and follow response to therapy.,,,,
Focal adrenal lesions in pediatric population may include a neoplasm, hemorrhage, infection, or cyst. Majority of adrenal masses present with abdominal pain and a palpable lump, some may be asymptomatic and diagnosed incidentally.,, This article highlights the imaging features of common adrenal masses that may involve the adrenal gland in pediatric population.
Primary adrenal neoplasms can be categorized by their origin (medulla or cortex) and function (hyperfunctional or nonfunctional). Primary medullary neoplasms include tumors of ganglion cell origin, which are derived from primordial neural crest cells. Neuroblastoma (NBL), ganglioneuroblastoma, ganglioneuroma, and pheochromocytoma constitute this group of tumors. Neoplasms that arise from adrenal cortex include adrenocortical carcinoma and adenoma. Teratoma, rhabdoid tumor, and smooth muscle tumor (leiomyoma) in acquired immunodeficiency syndrome patient are some rare neoplasms involving the adrenal gland.,,
Adrenal medullary neoplasms
NBL [Figure 1] is the third most common pediatric malignancy after leukemia and central nervous system tumors. More than 90% of NBLs present in children between 1 and 5 years of age, with peak incidence at age of 2 to 3 years. NBL may be seen antenatally or in newborns; unlike NBL seen in older children, it has a good prognosis.,, NBLs may arise from the adrenal glands (35%) or follow the paraspinal sympathetic chain ganglia from the neck to the pelvis (30%–35%); mediastinum may also be involved (20%). Most children present with a large abdominal mass and symptoms due to advanced disease. Skin metastases produce blueberry muffin skin. Periorbital bony and soft tissue metastases may result in ecchymosed orbital proptosis (raccoon eye) [Figure 1]b or blindness due to optic nerve compression. Bone metastases may produce skeletal pain. Massive hepatic metastases can cause increased intraabdominal pressure and death from respiratory insufficiency. Metastases to lung and brain are less common despite hematogenous dissemination. Intraspinal tumor extension results in peripheral neurological deficit and neurological symptoms from nerve root or cord compression. Intraspinal extension is more common with thoracic NBL as compared to retroperitoneal NBL and NBL of adrenal origin. Cervical NBLs may be associated with Horner’s syndrome, stridor, or dysphagia. Symptoms due to hormone production may be seen; increased serum catecholamine level can lead to high blood pressure and increased level of vasoactive intestinal peptide may cause diarrhea. Increased urinary catecholamines (seen in >90% of cases beyond infancy) is usually helpful in cases of suspected NBL. NBLs may also present with paraneoplastic syndrome.,,,,
|Figure 1 Neuroblastoma. (a) Ultrasound and CT abdomen of a 4-year-old male patient demonstrate a large left suprarenal mass with calcification (white thick arrows). The lesion appears hypoechoic/hypodense on USG/NCCT and shows heterogeneous enhancement on contrast-enhanced CT. The mass is extending from diaphragm below, encasing the adjacent vessels (white thin arrow) and invading the ipsilateral psoas muscle (arrowhead). The kidney is displaced anterolaterally. Aortocaval lymphadenopathy (black thin arrow) is seen. The lesion showed avid MIBG uptake. Patient was VMA +ve. (b, c) Two different patients of neuroblastoma. One of the patient (1b) shows ecchymotic orbital proptosis − “Raccoon eye” due to metastatic involvement of periorbital bones and soft tissues (arrow). Another patient (c) shows dural and calvarial metastases (arrows) with sun ray type of periosteal reaction. (d–f) Contrast-enhanced MRI spine (e) of another 7-year-old male patient with severe backache and fever showed a right adrenal mass (not shown), and multiple vertebral (arrowheads) and dural metastases (thin black arrows) with compression of dural sac. MRI brain (d) of the same patient showed a solitary ring enhancing metastatic lesion in right frontal lobe of brain (thin white arrow) and intense leptomeningeal enhancement (thin black arrow). The right adrenal mass was also well demonstrated on abdominal ultrasound (not shown). Later, contrast-enhanced CT abdomen (f) was done for staging, which also well demonstrated the adrenal mass along with the skeletal metastases. Histopathology confirmed neuroblastoma. CT, computed tomography; MIBG, metaiodobenzylguanidine; MRI, magnetic resonance imaging; NCCT, noncontrast computed tomography; USG, ultrasonography; VMA, vanillylmandelic acid.|
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Two systems are used for staging NBL: the International Neuroblastoma Staging System (INSS) and the International Neuroblastoma Risk Group Staging System (INRGSS). INSS is a postsurgical staging system based on the tumor resectability, lymph node involvement, and metastases. INRGSS was developed to establish a consensus approach for pretreatment risk stratification and is based on the preoperative imaging characteristics of the tumor on CT or MRI and MIBG scintigraphy. This staging system does not include the lymph node involvement. According to the INRGSS criteria, stage L1 applies to localized tumor not involving vital structures, stage L2 refers to locoregional tumor with presence of one or more image-defined risk factor, stage M refers to distant metastatic disease, and stage MS correspond to metastatic disease in children younger than 18 months with metastases confined to skin, liver, and/or bone marrow, and with <10% tumor cells in bone marrow aspirates. The prognosis depends on the stage of the tumor, age of presentation, and the site of origin. Lower tumor stage, age <1 year (especially perinatal NBL) at the time of diagnosis, and extraabdominal tumor origin have favorable prognosis.,
The initial diagnosis of NBL is usually made by US. The cross-sectional imaging techniques (MDCT or MRI) are standard imaging modalities for better delineation of the primary tumor, its relationship to the adjacent structures, and tumor staging. MRI is preferred for staging and follow-up in children because of lack of radiation exposure. On imaging, the NBLs [Figure 1] are usually solid and heterogeneous in appearance due to presence of calcification, cystic/necrotic changes, and hemorrhage. Adrenal hemorrhage associated with perinatal NBL makes the evaluation complicated. Neonates often present with large bilateral cystic NBLs with intracystic hemorrhage. NBL is commonly a poorly marginated mass, frequently extending across the midline and sometimes also into the chest. The criterion of NBL “crossing the midline” is defined as contiguous extension and invasion of the vital structures beyond the opposite side of the vertebral bodies. A large adrenal tumor overhanging the midline would not fit into this criterion. NBL may be mistaken for an intrarenal mass as it invades the kidney. Renal invasion occurs in approximately 20.4% of cases of abdominal NBL. Intraspinal extension, bone marrow infiltration, and encasement/displacement or invasion of blood vessels is best depicted on MRI without intravenous contrast. Contrast enhancement suggests vascularity of the lesion. NBL metastasizes to the skin, liver, lung, lymph nodes, and bone marrow. NBLs show MIBG uptake as seen with pheochromocytoma and other catecholamine-producing tumors. Catecholamine metabolites like homovanillic acid and vanillylmandelic acid are detected in blood or urine of 90% patients with NBL. Approximately 90% of NBLs are MIBG avid with sensitivity and specificity of about 90% to 99% for both primary and metastatic disease. All metastatic sites (including soft tissue, bone marrow, and cortical bone involvement) can be assessed by MIBG scan. Bone marrow involvement is confirmed by bone marrow biopsy and smears.,, Fusion study like PET-CT/SPECT-CT is more sensitive than MIBG in detecting tumor recurrence, because the initial MIBG-positive tumor may become MIBG-negative when it recurs. Follow-up after surgery and/or chemotherapy may be performed with CT, MRI, MIBG, or PET-CT. Different therapies have been recommended for different risk groups. Low-risk group patients are either simply observed or cured by surgery alone. Intermediate-risk group patients are treated with surgery and chemotherapy. High-risk group patients require intensive chemotherapy, radiotherapy, surgery, and immunotherapy.
Important differentials that need consideration include adrenal hemorrhage, intraabdominal extralobar pulmonary sequestration, and mesoblastic nephroma (primary renal tumor) during antenatal period and in neonates, and Wilms’ tumor in children >1 year of age.,,
Ganglioneuroblastoma [Figure 2] is a potentially malignant ganglion cell tumor. One-third of cases arise in the adrenal gland, one-third in retroperitoneum, and one-third in posterior mediastinum. Symptoms and imaging characteristics resemble those of NBL and ganglioneuroma.,
|Figure 2 Ganglioneuroblastoma. (a) Ultrasound and CT abdomen of a 5-year-old child with pain in abdomen show a well-defined right suprarenal mass. The mass appears hypoechoic/hypodense on USG/NCCT and shows minimal enhancement on postcontrast CT. The mass is causing minimal compression of IVC (better seen on MPR image). Photograph of the surgical specimen (b) shows a solid mass. H&E stained slide (c) shows ganglion cells with fibrillary stroma. CT, computed tomography; H&E, haematoxylin & eosin; IVC, inferior vena cava; MPR, multiplanar reformation; NCCT, noncontrast computed tomography; USG, ultrasonography.|
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Ganglioneuroma is a histologically benign tumor. It may arise de novo or may develop from maturation/transformation of a previous malignant NBL. Majority arise in the posterior mediastinum, one-third may occur in retroperitoneum, and adrenal gland involvement is rare. Ganglioneuromas occur in older children and are often diagnosed incidentally on abdominal US or chest radiograph. In contrast to NBL, urinary catecholamine levels are usually not raised. On imaging, the tumor resembles NBL; however, definite diagnosis is made on histopathology. It may be associated with neurofibromatosis type 1.,
Adrenal pheochromocytoma [Figure 3], known as intraadrenal paraganglioma, usually arises from chromaffin cells in adrenal medulla. One-third of pheochromocytomas (extraadrenal paragangliomas) may arise from sympathetic chain in the neck, mediastinum, or the abdomen. Pheochromocytoma is an uncommon pediatric neoplasm that usually presents in older children. Sweating, tachycardia, headache, nausea, and vomiting are common presenting symptoms. Hypertension in children is nearly always sustained rather than paroxysmal. Raised plasma/urinary catecholamines and their metabolites help in diagnosis. On imaging [Figure 3], these tumors are usually well-defined, rounded, and homogeneous in appearance; tumor size may range from 2 to 10 cm. Hemorrhage, necrosis, or calcification may be present. Pheochromocytomas typically show avid and intense contrast enhancement, with prolonged washout. Malignant pheochromocytoma is less common in children and is diagnosed by the presence of metastases. MIBG scintigraphy helps to determine multifocal disease. Pediatric pheochromocytoma may occur more commonly in association with multiple endocrine neoplasia type II, neurofibromatosis type I, von Hippel-Lindau disease, and hemihyperplasia; and these are frequently bilateral or multicentric within an adrenal gland.,,
|Figure 3 Pheochromocytoma. USG (a) and CT abdomen (b) of a 14-year-old male patient with headache and hypertension demonstrate bilateral suprarenal masses (thick white arrows). On ultrasound, isoechoic to hypoechoic masses were seen adjacent to bilateral kidneys and in paraaortic region on left side. On CT, enhancing bilateral suprarenal masses were seen without any calcification. The left suprarenal mass showed heterogeneous contrast enhancement with evidence of necrosis within it. The left paraaortic mass showed homogeneous contrast enhancement. Urinary/plasma VMA was raised. H&E stained slide (c) shows polygonal tumor cells with moderate amount of granular eosinophillic cytoplasm. CT, computed tomography; H & E, haematoxylin & eosin; NCCT, noncontrast computed tomography; USG, ultrasonography; VMA, vanillylmandelic acid.|
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Adrenocortical tumors (ACTs)
ACTs are very rare in children with a worldwide annual incidence of 0.3 per million children below 15 years of age. ACTs include benign adenomas, nodular hyperplasia, and adrenal cortical carcinoma [Figure 4]. Most tumors occur before the age of 5 years, with a female predominance. Unlike adults, most pediatric ACTs are hormonally active and present with endocrine abnormality. The overproduction of androgens leads to clinical symptoms of virilization in girls and precocious puberty in boys. Hypertension (seen in 43% cases) may be due to overproduction of mineralocorticoid (aldosterone) or glucocorticoid hormones. Hypertension usually resolves following tumor resection. Cushing’s syndrome (hypercortisolism) is relatively less common in children. Raised hormone levels are useful for diagnosis and detection of tumor recurrence during follow-up. ACTs may be associated with Beckwith-Wiedemann and Li-Fraumeni syndrome More Detailss. ACTs are usually small at the time of presentation, but larger lesions may occur. Small lesions are homogeneous, whereas larger lesions are heterogeneous (due to presence of hemorrhage, necrosis, and calcification) and show characteristic central scar. Tumor invasion into inferior vena cava is common. Lung, liver, and bone are the most common sites for distant metastases. Features favoring malignancy include large size (>5 cm), weight >200 g, inferior vena cava, or periadrenal soft tissue invasion and distant metastases. Histologic distinction between benign and malignant ACTs during childhood is not clear; hence, clinical, laboratory, and imaging follow-up is necessary.,,,
|Figure 4 Adrenal cortical carcinoma. Ultrasound (a) and CT image (b) of a 2.5-year-old girl with virilization show a large, well-defined, heterogeneous left suprarenal region mass (thick white arrow) with calcification. A characteristic echogenic star pattern was seen on ultrasound. The central nonenhancing hypodense area on contrast-enhanced CT is consistent with necrosis (asterisk). Thrombus within IVC is also evident (thin white arrow). CT, computed tomography; IVC, inferior vena cava.|
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Adrenal incidentaloma (AI) is an adrenal mass lesion >1 cm in diameter discovered incidentally during investigation for conditions unrelated to any suspicion of adrenal disease. AIs are extremely rare in children and, are found in 3% of people older than 50 years of age at autopsy. AIs may include an adrenal medullary neoplasm, an adrenal cortical tumor, or a metastatic deposit.,
Other adrenal neoplasms
Teratoma of adrenal gland may be detected perinatally. Neonates may present with a palpable abdominal lump and pain. A well-defined adrenal mass with fatty component and/or calcification favors teratoma. Increased serum α-fetoprotein is seen with malignant teratoma.
Malignant rhabdoid tumor is a rare pediatric malignancy that may involve the adrenal gland. It is a highly malignant tumor with poor prognosis. The imaging features are similar to NBL.
Nonneoplastic adrenal masses
Adrenal hemorrhage [Figure 5] typically occurs in the neonatal period. Predisposing factors include large babies, obstetric trauma, breech delivery, perinatal asphyxia, neonatal sepsis, and diabetic mother. Adrenal hemorrhage in older children may be associated with blunt trauma, anticoagulant therapy, vasculitis, and meningococcal infection. Hemorrhage occurs more frequently on right, and occasionally may be bilateral. On US [Figure 5], adrenal hemorrhage is usually echogenic. No blood flow is detected on Doppler study. Serial short-term follow-up US demonstrates progressive decrease in size, cystic transformation, and appearance of calcification in resolving adrenal hemorrhage. Adrenal NBL is an important differential. Doppler flow within the echogenic adrenal mass and interval growth favors adrenal NBL. The diagnosis of adrenal NBL may be complicated by presence of hemorrhage within the tumor.,
|Figure 5 Adrenal hemorrhage. Color Doppler ultrasound of a newborn shows a large heterogeneous left suprarenal mass without intralesional blood flow consistent with adrenal hemorrhage. Serial short-term follow-up ultrasound demonstrated progressive decrease in size, cystic transformation, and appearance of calcification in resolving adrenal hemorrhage (not shown).|
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Adrenal cysts [Figure 6] are rare in occurrence. They are usually asymptomatic and found incidentally. Most adrenal cysts are lymphatic malformations or hemorrhagic pseudocysts. Simple cysts [Figure 6] are rounded, thin-walled, fluid-containing structures, appearing hypo/anechoic on US, fluid attenuation lesions on CT, and hyperintense on MRI. Internal septations may be seen in lymphatic malformations.
|Figure 6 Adrenal cyst. Color Doppler ultrasound of a 14-year-old female shows a large well-defined, rounded fluid containing anechoic lesion in left suprarenal location without intralesional blood flow consistent with a simple adrenal cyst. The lesion was detected as an incidental finding on abdominal ultrasound.|
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Primary adrenal masses in the pediatric age group need to be differentiated from suprarenal extraadrenal masses like intraabdominal extralobar pulmonary sequestration, retroperitoneal lymphatic malformations, extramedullary hematopoiesis, and fat in suprarenal fossa. The age of the patient, clinical history, characteristic imaging features, and laboratory investigations help to narrow the differential diagnosis.,,
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]