1) Blood tests and urinalysis
Neuroblastoma cells produce substances called catecholamines that are released into the blood. As a result, the blood level of a hormone called norepinephrine exceeds the normal, which may be a sign of neuroblastoma. Catecholamines in the blood are also metabolized to vanillyl mandelic acid (VMA) and homovanillic acid (HVA), which are excreted in the urine. Thus, the levels of VMA and HVA in urine are higher than normal. Measurement of VMA and HVA in urine is useful to make a diagnosis. In addition, the blood levels of neuron-specific enolase (NSE), lactate dehydrogenase (LDH) and ferritin may be higher than normal.
2) Imaging tests
Imaging tests include ultrasound examinations, x-ray examinations, computed tomography (CT), magnetic resonance imaging (MRI), and radionuclide examinations. Neuroblastoma may be found by abdominal ultrasound or chest x-ray examinations by chance. MRI and CT can clearly identify the original site of the tumor and the relationship between the tumor and nearby organs and tissues, and is useful to detect the site of metastasis. Radionuclide examinations include metaiodobenzylguanidine (MIBG) scintigraphy and bone scintigraphy. MIBG scintigraphy is a useful and important test for diagnosis, detection of the site of metastasis, and evaluation of treatment efficacy because MIBG is specifically taken up by neuroblastoma cells. Bone scintigraphy is useful to detect bone metastasis.
3) Biopsy and pathology diagnosis
Biopsy is a surgical procedure to collect samples of tumor tissues etc., which is a very important test. A pathologist views the samples under a microscope to provide a definitive diagnosis (pathologic diagnosis). The tumor is also classified into the favorable or unfavorable prognosis group using the International Neuroblastoma Pathology Classification (INPC), an internationally recognized common standard, for risk assessment.
4) Bone marrow examinations
Neuroblastoma often metastasizes to the bone marrow. Microscopic bone marrow metastasis cannot be found by imaging tests, and therefore collection and direct examination of the bone marrow is necessary. Bone marrow examinations include bone marrow aspiration and biopsy. In both examinations, bone marrow tissues are collected by inserting a needle into the bone marrow. Biopsy is recommended to accurately detect metastasis, but bone marrow aspiration can be a substitute. Bone marrow examination of at least two sites, one each on the right and the left side, is performed, and a pathologist views the samples under a microscope to determine whether there is metastasis or not.