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Findings: There is an approximately 4 x 4 cm heterogeneously enhancing mass just superior to the left lung apex. There is extension through the T-1/2 neural foramina with compression of the thecal sac. In addition, there is compression of the left internal jugular vein with collateralization through the external jugular vein.
Diagnosis: Neuroblastoma.
Discussion: Neuroblastoma is one of the most common solid tumors of childhood. It is the third most common malignancy of childhood, with only leukemia and primary brain tumors exceeding it in incidence. Neuroblastoma is a malignant tumor derived from primitive neural glial cells. These tumors may arise anywhere along the sympathetic chain. In addition, these tumors may arise within the adrenal medulla.
Neuroblastoma is somewhat more common in males than females with a median age of diagnosis being 22 months. Approximately 79% of all neuroblastomas will present by four years of age. The most common presenting sign is an abdominal mass with general symptoms including fever, weight loss, and irritability. Common sites of metastasis include the skeleton, bone marrow, liver, and lymph nodes. In addition, neuroblastoma may metastasize to the skin. Neuroblastoma is derived from the same neural crest tissue as ganglioneuroblastoma and ganglioneuroma. These tumors are differentiated by the degree of cellular maturation with neuroblastoma being a frankly malignant tumor and a ganglioglioma being a benign tumor. Ganglioneuroblastoma is considered an intermediate form between these two. The majority of neuroblastomas are located within the abdomen, two thirds of which arise from the adrenal gland. There are two unusual paraneoplastic syndromes which may occur with neuroblastoma. The first is myoclonic encephalopathy of infancy which is a triad of opsoclonus, myoclonus and cerebellar ataxia. The second paraneoplastic syndrome consists of watery diarrhea, hypokaliemia, and achlorhydria. This may present in approximately 7% of patients with neuroblastoma. Computed tomography often demonstrates a lobulated mass usually located within a suprarenal region, but often within a paravertebral region. There may be hemorrhage, necrosis, and calcification which will cause inhomogeneous attenuation as well as enhancement. Calcification is identified in approximately 85% of patients with neuroblastoma. MRI is the best imaging modality for demonstrating extension through the neural foramina as well as epidural extension and cord compromise. Prognostic factors are highly dependent on the age of the patient diagnosed with older patients having a significantly worse prognosis.
References:
Dietrich RD. Neuroblastoma; The Role of MR Imaging.
AJR May 1987;148:937-942.
Kirks D. Practical Pediatric Imaging. Lippincott, Philadelphia;
1998:1126-1136.
Edelman RR. Clinical MRI Volume 2, W. B. Saunders, Philadelphia;
1996:1290.
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