American Urological Association - Neuroblastoma (NB)
- Most common solid neoplasm of childhood other than CNS tumors.
- Traditionally divided into three: NB, ganglioneuroblastoma (GNB) and ganglioneuroma (GN), from most immature to mature; majority are NB.
- Patients are almost exclusively small children <4 years old.
- Mostly sporadic or associated with Beckwith-Wiedemann syndrome, neurofibromatosis, and Hirschsprung's disease.
- May show MYCN amplification, not specific but useful for prognosis.
- Increased levels of catecholamines and metabolites present.
- Gross: soft fleshy relatively well-circumscribed mass (image A) & (image B).
- Cells have dark, dusty blue nuclear chromatin and minimal cytoplasm ("small round blue cell" tumor) (image C).
- Vaguely nodular growth pattern.
- Homer-Wright rosettes a characteristic feature (seen in only 30%) which consist of a ring-like arrangement of neoplastic cells with a central area of pink neuritic process. No central lumen in the rosettes (image D).
- Maturation is evidenced by ganglionic differentiation (more eosinophilic cytoplasm, large eccentric nucleus with prominent nucleolus [owl's eye]).
- Poorly differentiated if <5% ganglion differentiation.
- Immunohistochemistry: NB84+, neurofilament+, chromogranin+ and synaptophysin+.
- Prognosis depends on multiple variable (age, histologic features, stage, as well as some molecular (MYCN, DNA ploidy) and genetic (Ch3 1p36, Ch 17q gain).
- Can metastasize by lymphatics or blood, and commonly to skeletal system especially skull and orbit (Hutchinson's syndrome) and to liver (Pepper's syndrome).
- DDX: other pediatric small round blue cell tumor such as Ewing sarcoma/primitive neuroectodermal tumor (PNET) (CD99+), rhabdomyosarcoma (desmin+), Wilms' tumor (WT1+) and lymphoma (CD45+).