A 10-month-old female patient presented with a 1-month history of
irregular fever and abdominal distension. On examination, she was
found to have bilateral, upper-quadrant flank masses.
Diagnosis
Neuroblastoma. Serum and urine catecholamine levels showed mild
elevation of serum homovanillic acid (HVA) and urine
vanillylmandelic acid (VMA). Histological study confirmed the
diagnosis of neuroblastoma.
Findings
Sonography of the abdomen demonstrated a bilateral, mixed echogenic
mass, enveloping the upper poles of the kidneys. These masses
flattened and displaced the kidneys inferiorly (Figure 1).
Computed tomography (CT) showed bilateral large masses in the
paravertebral region, compressing the upper poles of the kidneys,
and crossing the midline, displacing vessels (Figure 2). No
calcifications were present in either mass and there was no
retroperitoneal adenopathy or hepatic abnormality.
Discussion
Neuroblastoma is a poorly differentiated neoplasm derived from
neural crest cells. It is one of the most common malignant tumors
of childhood, with 40% arising in the adrenal glands. Bilateral
adrenal involvement from synchronous development or metastatic
spread of the tumour is seen in less than 10% of children with
neuroblastoma. More than one third of cases (36%) are diagnosed in
children younger than 1 year. The male-to-female sex ratio is 1.2
to 1. Some patients exhibit a hereditary predisposition for
neuroblastoma, such as in cases with apparent familial, bilateral
or multifocal disease. In these subsets of patients, the median age
at diagnosis is 9 months.1-3
Neuroblastoma has been called "the great mimicker" because of
its myriad clinical presentations related to the site of the
primary tumour, metastatic disease and its metabolic tumor
by-products. Most neuroblastomas produce catecholamines, which
result in some of the most interesting presentations observed in
children with neuroblastoma. For example, Kerner-Morrison syndrome
causes intractable secretory diarrhea, resulting in hypovolemia,
hypokalemia, and prostration.1-3
On ultrasonography, an adrenal neuroblastoma appears as a
suprarenal heterogeneous echogenic mass. Ultrasonography can show
urinary obstruction, vascular displacement and compression, nodal
involvement, tumor extent, and liver involvement. However
neuroblastomas are often large, and when they spread throughout the
abdomen and/or into the chest, ultrasound may not be able to
define their precise edges. It has limited ability to detect
metastases in retroperitoneal and retrocrural lymph nodes and is
usually unable to detect extradural extension
oftumors.4-5
On CT, neuroblastoma appears as a lobulated, soft-tissue mass,
either homogeneous or heterogeneous, which is caused by
hemorrhage,necrosis, and/or calcification.
Calcification has been reported on CT in approximately 85% of
patients. CT can show prevertebral extension of tumor across the
midline as well as encasement of the celiac axis or superior
mesenteric artery by the neuroblastoma. It can also show extension
of tumor to retroperitoneal lymph nodes, to the liver, around
central vessels, and into the vertebral canal. CT is excellent for
demonstrating retrocrural and paravertebral tumor extension to the
chest, common in abdominal neuroblastoma.4-7
Magnetic resonance imaging (MRI) is excellent for evaluating the
location, extent and spread of neuroblastoma and the tumor shows
equal or lower signal intensity on T1-weighted images and higher
signal intensity on T2-weighted images compared with muscle. The
center of the tumor is often heterogeneous, reflecting the
presence of hemorrhage, necrosis or calcification. Advantages
of MRI over CT and ultrasonography include: multiplanar imaging
(useful for assessing invasion of adjacent organs); detection of
extradural tumor extension; identification of bone marrow
metastases (useful for staging); and, delineation of
intra-abdominal vascular displacement or encasement without using
intravenous contrast media.5-7
The treatment of neuroblastoma depends on the age of the child
and the stage of the tumor. Surgery is indicated for stage 1 and 2
tumors while chemotherapy and radiation are the primary treatment
modalities for advanced tumors.
CONCLUSION
The bilateral neuroblastoma is a rare entity. Medical imaging is
very helpful in the diagnosis and the staging of this tumor.
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