In the diagnosis for neuroblastoma, why should a tissue sample be taken?

Diagnosis- prognosis: Neuroblastoma diagnosis can be confirmed with a tissue biopsy. The biopsy can also give prognostic information- an assessment of tumor aggressiveness and likely results with treatment. Tissue can help assess neuroblastoma sub-types, aggressive characteristics can be seen on microscopy and genetic mutations can be tested which in turn confer a worse outcome.

Identification: A biopsy is required to confirm the diagnosis of neuroblastoma. The information will help dictate the need for further surgery, what type of chemotherapy is required. Various chemos have toxic side effects, so it pays to make sure it is needed by confirming the presence or absence of neuroblastoma.

Staging: Beyond confirming the diagnosis, tissue is needed for neuroblastoma staging which then determines the therapy that will be recommended. You need to know if the tumor has "favorable" or " not favorable" appearance under the microscope as well as if certain genetic changes are present in the tumor tissue (myc amplification and others) to fully stage the tumor and recommend appropriate therapy.