Health is Wealth

MORPHOLOGICAL FEATURES

Gross
neuroblastomas are usually large,soft,grey and relatively well circumscribed;areas of hemorrhage,necrosisand calcification are often present.some time hemorrhage is so extensive as to mimic hematoma.cystic degeneration also occur.
Microscopy
The pattern of growth is vaguely nodular as a result of delicate,incomplete fibrous septa.the tumor cells are small and regular,slightly larger than small lymphocyte.Homer-wright’s rosettes are present,characterized by collection of tumor cells around a central area filled with a fibrillary material,which is mass of nuerites as revealed by silver stains.

ELECTRON MICROSCOPY
Ultra structurally , neuroblastoma cells are characterized by the presence of neuritis ,neurosecretory granules and synaptic endings the neuritis form a complex interdigitating meshwork in the centre of rosette
Immunohistochemistry
Neuroblastoma cells expresses neuron-specific enolase, neurofilaments, neurofilament-66/a-internexin, peripherin, chromogranin, synaptophysin, secretogranin 2, vasoactive intestinal peptide, microtubule associated proteins, NB 84, nerve growth factor receptors and other neuron related antigens including cell surface ganglioside GD2. Expressoin of Insulin- like growth factor 2 is associated with a lobular growth pattern and good cytological differentiation.
Neuroblastoma produce catecholamines which can be demonstrated in sections or touch preparations by the twchnique of formaldehyde- induced fluorescence.
Chromosomal and molecular markers
During last 2 decade, many chromosomal and molecular abnormalities have been identified in neuroblastoma. these biologic markers have been evaluated to determine their value in assigning prognosis,and some of these have been incorporated in to the stratergie sused for risk assignment
The most important of these biologic markers is MYCN ,which is over expressed oncogene in neuroblastoma with amplification of distal arm of chromosome 2.it is amplified in approximately 25% of do novo cases and is more common in patients with advanced-stage disease,and is marker of poor prognosis.in contrast to MYCN ,H-ras oncogene correlates with lower stage of the disease.
Deletion of short arm of chromosome 1 is most common chromosomal abnormality, which confers poor prognosis. Other alleic losses of chromosomes 11q, 14q, 17q and gain of chromosome 1 have been reported.
DNA index is another useful test that correlates with response to therapy in infants. Look.et al demonstrated that