2Neoplasms of infancy and childhood Benign>malignantIncidence of malignancy:1-15 yrs /10,000 /year but leading cause of death after accidents in the West. (developing countries??)Most malignant tumours in children arise from hematopoietic,nervous and soft tissues (adults –epithelial)
3Difference between adult & Paed tumours Association between abnormal development (teratogenesis) & tumour induction.Prevalence of constitutional genetic abnormalities or syndromes that predispose to cancerTendency of malignancy to undergo differentiationImproved survival
5Sacrococcygeal teratomas Germ cell neoplasm1:40,000 live birthsMass in the sacrum and buttocksComposed of elements of > 1 germ cell layer.mixture of elements.Neural origin determines the behaviour< 2 months-benign.
8Small,round, blue cell tumours 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.
10Pathology of neuroblastoma Site :Paravertebral, Posterior mediastinum, abdomen ,Adrenal 1/3Gross appearance:Nodular, of varying sizeMay be encapsulated or infiltrativeCut section: grey-tan, soft and friableVarigated,necrosis,hemorrhage, calcificaton,cystic change
17Retinoblastoma Malignant tumour of the eye in childhood Neuroepithelial origin –posterior retinaFamilial, %, associated with germ line mutation, heritable.Sporadic:30-40%,somatic gene mutation.Associated with Rb 1 geneSecondary malignancy –osteosarcoma
18RB 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 fromG1 to STumour supressor geneIf both RB genes are abnormal i.e. mutated or have a missing allele, it permits unregulated cell proliferation.Knudson’s two-hit hypothesisPeople with RB mutations are susceptibe to malignancies especially osteosarcoma