What Is Childhood Neuroblastoma

Summary

Neuroblastoma is one of the most common tumors in children derived from primordial neural crest cells that are precursors of the sympathetic nervous system. NBLs consist of undifferentiated, immature, small, rounded-shaped sympathetic neurons, neuroblasts with little cytoplasm, small indistinct and darkly coloured nuclei, however, the most common primary sites of NBL development are the adrenal medulla, retroperitoneum, and extra-adrenal paraspinal ganglia.

Introduction

Neuroblastomas (NBLs), along with ganglioneuroma and ganglioneuroblastoma, form a group of ganglion cell-derived tumors derived from primordial neural crest cells that are precursors of the sympathetic nervous system​1​, in fact, neuroblastoma is one of the most common tumors in children and has extremely diverse manifestations and clinical behaviour. However, NBL is the second most common abdominal cancer in children after Wilms’ tumour and the third most common malignant tumor in children after central nervous system tumors and leukaemia​2​.

Overall, it accounts for approximately 15% of childhood cancer mortality​3​ and reflects the aggressive nature and incidence of metastasis at the time of diagnosis. In fact, most NBL deaths occur within two years of diagnosis​4​.

NBL is not considered to be part of a developmental, congenital or genetic syndrome and is not associated with other malformations, in fact, no one has identified the factors behind the epidemiology of exogenous.

NBL is the most common (30–50%) malignancy in the first month of life and in fact, this tumor has an excellent prognosis. Neonatal NBL is due to adrenal metastasis (bone marrow, liver, and skin) usually reported being present in approximately half of the patients at the time of diagnosis. Despite their metastatic spread, these tumors generally have favourable biological behaviour and >90% survival​2​.

Sites of Origin

The NBL originates in the adrenal gland, in the organ of the Zuckerkandl, or it follows the distribution of sympathetic ganglia from the neck to the pelvis in the perispinal region. However, the most common primary sites of NBL development are the adrenal medulla (35%), retroperitoneum, and extra-adrenal paraspinal ganglia (30–35%), followed by mediastinum (20%)​1​. The origin of cancer at the pelvis (2%–3%) and neck (1%–5%) are uncommon but significant. Abnormal primary locations such as the lung, thymus, kidney, stomach, mediastinum, and cauda equina have been reported​2​. Sometimes, the doctors may not detect the primary tumor in metastatic disease​2,3​.

Histological features

NBLs consist of undifferentiated, immature, small, rounded-shaped sympathetic neurons, neuroblasts with little cytoplasm, small indistinct and darkly coloured nuclei. Sometimes clusters of cells called Horner-Wright rosettes form and are characteristic of NBL​3,5​. NBL is diagnosed by high levels of single catecholamines in the urine with typical histopathological findings​2​.

Two histological systems are commonly used to classify neuroblastic tumors into risk groups based on histological features and prognosis: the Shimada classification and the POG (Paediatric Oncology Group) classification.

According to the POG, NBLs, which contain less than 50% differentiated elements, can be further divided into “undifferentiated” (immature form), “poorly differentiated”, or “differentiated” (mature form).

The Shimada classification combines morphological and histological features with the patient’s age at the time of diagnosis. In fact, the doctor assigns a “favourable” or “poor” morphology based on a combination of patient age, cellular and stromal maturity, and mitosis-karyorrhexis index (MKI)​3​.

References

  1. 1.
    Rha S, Byun J, Jung S, Chun H, Lee H, Lee J. Neurogenic tumors in the abdomen: tumor types and imaging characteristics. Radiographics. 2003;23(1):29-43. doi:10.1148/rg.231025050
  2. 2.
    Kushner B. Neuroblastoma: a disease requiring a multitude of imaging studies. J Nucl Med. 2004;45(7):1172-1188. https://www.ncbi.nlm.nih.gov/pubmed/15235064
  3. 3.
    Lonergan G, Schwab C, Suarez E, Carlson C. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographics. 2002;22(4):911-934. doi:10.1148/radiographics.22.4.g02jl15911
  4. 4.
    Boubaker A, Bischof D. Nuclear medicine procedures and neuroblastoma in childhood. Their value in the diagnosis, staging and assessment of response to therapy. Q J Nucl Med. 2003;47(1):31-40. https://www.ncbi.nlm.nih.gov/pubmed/12714952
  5. 5.
    Hiorns M, Owens C. Radiology of neuroblastoma in children. Eur Radiol. 2001;11(10):2071-2081. doi:10.1007/s003300100931