This document discusses two childhood tumors - neuroblastoma and retinoblastoma. Neuroblastoma originates from neural crest cells and most commonly presents as an adrenal or sympathetic ganglia tumor. Microscopically, it appears as sheets of small, round, blue cells that may show maturation. Prognosis depends on factors like stage, age, MYCN gene amplification. Retinoblastoma is a malignant eye tumor of childhood caused by mutations in the RB1 tumor suppressor gene. Microscopically, it resembles neuroblastoma and may form Flexner-Wintersteiner rosettes. Both tumors can spread widely if not treated.

1. Belgorod State National Research University
Department: Pathological Anatomy.
Topic: Childhood Tumors.
Compiled by:
N. K. Gaur

2. Small,Round, Blue Cell Tumors in Childhood.
 Primitive appearance (not anaplastic or pleomorphic)
 Sheets of small,round,blue cells (with dark nuclei,scant
cytoplasm,indistinct borders.)
 May show features of organogenesis specific to the tissue
of origin.

4. Neuroblastoma
 Embryonal malignant tumour
 Neural crest origin
 Neoplastic neuroblasts
 Site: adrenal medulla &sympathetic ganglia
 7-10% of solid paediatric malignancies.
 Sporadic occurance.
 Rarely familial (bilateral,multifocal)

7. Pathology of Neuroblastoma.
Site :Paravertebral, Posterior mediastinum, abdomen ,Adrenal
1/3
Gross appearance:
Nodular, of varying size
May be encapsulated or infiltrative
Cut section: grey-tan, soft and friable
Varigated, necrosis, hemorrhage, calcification, cystic change

8. Microscopy of Neuroblastoma
Sheets of small, round, blue cells with dark nuclei, scant cytoplasm,
indistinct borders.
Mitosis++, Karyorrhectic debris +
Pleomorphism +/-
Homer-Wright rosettes, Neuropil.
Maturation: Schwann cell, stroma &ganglion cell differentiation.

9. Microscopy of Neuroblastoma.

10. Clinical features.
 Abdominal mass, fever
 Blueberry muffin
 Wide metastasis
 Secrete catecholamines
 Vanillylmandelic acid (VMA)/Homovanillic acid (HVA) screening.

11. Prognosis
 Stage
 spread to regional lymph nodes,liver,lungs,bones etc
 Age :< 1 yr.
 Morphology –gangliocytic differentiation better
 MYCN (N myc) gene amplification-worse.

12. Retinoblastoma
 Malignant tumour of the eye in childhood
 Neuroepithelial origin –posterior retina
 Familial,- 60-70%, associated with germ line mutation, heritable.
 Sporadic:30-40%,somatic gene mutation.
 Associated with Rb 1 gene
 Secondary malignancy –osteosarcoma

13. RB gene
 RB gene is on chromosome 13
 RB gene function is the most critical checkpoint in the cell cycle and
allows the cell to enter from
G1 to S
 Tumour supressor gene
 If both RB genes are abnormal i.e. mutated or have a missing allele, it
permits unregulated cell proliferation.
 Knudson’s two-hit hypothesis
 People with RB mutations are susceptibe to malignancies especially
osteosarcoma

15. Morphology of retinoblastoma.
 Gross: occular masses.
 Microscopy: Sheets of small,round,blue cells with dark nuclei,scant
cytoplasm,indistinct borders
 Flexner-Wintersteiner rosettes.

16. Morphology of retinoblastoma.

17. Behaviour .
 Spread through optic nerve or to subarachnoid space to CNS, bone,
lymph nodes.
 Cure with treatment.
 Spontaneous cure.
 Second malignancy.