Chapter 54 Neuroblastoma
PATHOPHYSIOLOGY
Neuroblastomas are soft, solid tumors originating from neural crest cells that are precursors of the adrenal medulla and sympathetic nervous system. Neuroblastomas can occur wherever sympathetic nervous tissue is found. The majority of tumors are usually in the abdomen, either in the adrenal gland or the sympathetic ganglia. Less common primary sites include the paraspinal area of the thorax, the neck, and the pelvis. Neuroblastomas often impinge on adjacent tissues and organs and can metastasize to the lymph nodes, bone, bone marrow, and/or subcutaneous tissue. Researchers are studying genetic mutations in the neuroblastoma cells as they seek to identify the etiology of neuroblastoma.
INCIDENCE
1. Neuroblastoma is the most common extracranial solid tumor of childhood and the most common neoplasm of infants.
2. It is the second most common type of childhood tumor.
3. Approximately 650 new cases are diagnosed each year in the United States.
4. The estimated incidence is 1 in 7000 births.
5. Neuroblastoma most commonly occurs in children between birth through the fourth year of life.
6. The unique phenomenon of spontaneous tumor regression and maturation into benign forms may allow many cases of neuroblastoma to go undetected.
7. Survival rates are 90% in low-risk patients, 70% to 90% in intermediate-risk patients, and 30% in high-risk patients (see Medical and Surgical Management section in this chapter).
CLINICAL MANIFESTATIONS
COMPLICATIONS
1. At diagnosis: Depending on the location of the tumor, neuromuscular complications can include lower-extremity weakness or paralysis. A hematologic complication is metastasis to lymph nodes, bone, and bone marrow.
2. During treatment: Adverse events from chemotherapy, radiation therapy, and/or surgery can be life-threatening. These can include infection and organ toxicities.
LABORATORY AND DIAGNOSTIC TESTS
1. Complete blood count—to detect anemia caused by many secondary factors (e.g., hemorrhage, disseminated intravascular coagulation)
2. Urinary levels of catecholamines (vanillylmandelic acid and homovanillic acid)—tumor markers that are elevated owing to overproduction by tumor cells or defective storage within tumor cells
3. Ferritin level—increase correlates with poorer prognosis
4. Neuron-specific enolase level—elevated owing to correlation with amount of active neuronal tissue
5. Bilateral bone marrow aspiration and biopsies—to reveal marrow involvement, confirm diagnosis, and allow staging
6. Chest radiographic study—to delineate primary thoracic neuroblastoma and vertebral and paravertebral involvement
7. Computed tomography and magnetic resonance imaging—to determine extent of disease
8. Bone scan—to assess for metastasis
9. Metaiodobenzylguanidine (MIBG) scan—to assess involvement of bone and tissue. An MIBG scan provides a scintigraphic image of neuroendocrine tumors.
