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Neuroblastoma Diagnosis
Last reviewed: 23.04.2024
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Routine clinical trials with neuroblastoma include anamnesis, physical examination, an expanded blood test, urinalysis, a biochemical blood test with the obligatory study of lactate dehydrogenase activity and ferritin concentration. The most probable reason for increasing the amount of ferritin is an increase in its synthesis by tumor cells with subsequent secretion into the blood plasma.
Visualization of the tumor is possible by various methods (ultrasound, radiography, CT, MRI), each of which has certain advantages. The combination of methods makes it possible to get the most complete picture of the process. The tumor volume is calculated by multiplying three mutually perpendicular dimensions, expressed in centimeters, and dividing the resulting product by 2.
The diagnosis of neuroblastoma is morphologically examined in the study of a biopsy material obtained from a primary tumor or metastases, or in the detection of bone marrow damage in combination with an increase (more than three times the normal values) of the concentrations of catecholamines or their derivatives in the blood or urine.
To derivatives of catecholamines, which have a special diagnostic value in neuroblastoma, include vanillilmindal, homovelinic acid and dopamine. The concentration of vanillylmandal and homovanilic acid was increased in 85% of patients, dopamine concentration in 90% of patients. Excretion of catecholamines has no prognostic significance, but the high ratio of vanillylmandal and homovanilic acids indicates the presence of a low-grade tumor and is associated with a worse prognosis (the relationship is directly proportional).
An additional diagnostic marker for neuroblastoma is neuron-specific enolase, isolated by neuroendocrine tumor cells, determined by immunohistochemical examination. The high activity of this enzyme indicates a high prevalence of the process. Other markers of neuroblastoma are GD 2 ganglioside , chromogranin A, neuropeptide Y. It should be noted that none of the listed indicators are specific for this type of tumor.
Osteoscintigraphy with 99mTc and subsequent radiography of identified isotope hyperfixation foci is used to visualize possible bone metastases.
Scintigraphy with denguguan (M-iodobenzylguanidine, I 131 ) has certain advantages, since this isotope selectively accumulates on the catecholamine receptors of neuroblastoma cells, due to which it is possible to visualize both the primary tumor site and metastases. The day before the study and within 3 days after it is necessary to take potassium iodide in order to protect the thyroid gland.
Aspiration bone marrow biopsy (from 4-8 points) is included in the mandatory diagnostic minimum for suspected neuroblastoma, as the bone marrow is affected in 10% of cases. As an additional method of research, bone marrow trepanobiopsy is used.
All foci suspicious for metastases need to be biopsy.
To verify the diagnosis of neuroblastoma, the morphological study is complemented by immunohistochemical and molecular-biological. This is especially important when conducting differential diagnosis between small cells called small-cell tumor (lymphoma, primitive neuroectodermal tumors, rhabdomyosarcoma).
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