Neuroblastoma

Basics

Description

  • Neuroblastoma is a “small round blue cell tumor” of childhood which arises from developing neural crest cells in the sympathetic nervous system.
  • The clinical behavior of neuroblastoma is amazingly diverse. Some tumors undergo maturation into benign ganglioneuroma or even spontaneously regress without therapy, whereas others inexorably progress despite intensive treatment.
  • Behavior of neuroblastoma tumors can often be predicted by combining clinical features (age, stage) with pathologic/molecular features (histologic characteristics, tumor ploidy, MYCN amplification, 1p, and 11q23 status).
  • Integrating clinical and molecular features allows for appropriate risk stratification so that treatment can be tailored to the risk of recurrence. Current risk stratification identifies three separate groups of patients with different prognoses and treatment strategies:
    • Low-risk patients: localized tumors and/or favorable clinical and molecular features
    • Intermediate-risk patients: more extensive primary tumor or regional disease or unfavorable clinical and molecular features
    • High-risk patients: patients >18 months with metastatic disease or unfavorable molecular features

Epidemiology

  • The median age at diagnosis is 19 months, with 89% of cases diagnosed <5 years of age. Fewer than 5% of patients are diagnosed >10 years of age.
  • The male-to-female ratio is 1.1:1.
  • The majority of tumors arise in the retroperitoneum, with the adrenal gland being the single most common location.

Incidence

About 800 new cases per year in the United States (10 per million children per year)

Prevalence

  • Accounts for 8–10% of all childhood cancer, making it the most common extracranial solid tumor and the most common cancer overall during the first 2 years of life
  • Accounts for 15% of all pediatric cancer deaths
  • Occurs in 1 per 7,000 live births

Risk Factors

Genetics

  • Most cases arise spontaneously. 1% are familial (autosomal dominant) and are usually associated with ALK mutations.
  • Patients with associated congenital central hypoventilation syndrome often have PHOX2B mutations.
  • Low-risk patients usually have hyperdiploid tumors with increased chromosome number, whereas high-risk patients more often have segmental chromosome abnormalities such as MYCN amplification and are either near diploid or near tetraploid.

Pathophysiology

Tumor growth can cause symptoms in multiple ways:

  • Neurologic: nerve or cord compression from paraspinal tumors, such as the development of Horner syndrome from a posterior mediastinal mass
  • Hypertension: from renal artery distortion or occasionally from excessive catecholamine release
  • Pain: from metastatic bone disease or abdominal distension
  • Hematologic: pancytopenia from marrow disease
  • Skeletal: proptosis or periorbital ecchymosis from skull metastases
  • Dermatologic: subcutaneous bluish skin nodules seen in infants

Etiology

No known etiology or causative environmental exposures

Commonly Associated Conditions

May occur along with other disease that have dysregulation of the peripheral nervous system, such as neurofibromatosis type I, Hirschsprung disease, or central congenital hypoventilation syndrome

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