How Does Olfactory Neuroblastoma Affect The Body & What Triggers It?

The olfactory neuroblastoma is a rare malignant tumor originating from cells of the neural crest and the development of the olfactory epithelium of the nasal cavity.

Presumably, the tumor originates from the basal cells of the olfactory epithelium. On histological examination, the tumor is similar to undifferentiated small cell carcinoma, which may lead to cases of incorrect diagnosis.

How Does Olfactory Neuroblastoma Affect The Body?

Neuroblastomas account for 2-3% of all malignant tumors of the nasal cavity and about 0.3% of all malignant tumors of the upper respiratory and digestive tracts. The etiology is unknown. The olfactory neuroblastoma is characterized by aggressive growth; it often grows in the paranasal sinuses, cranial cavity, and the orbit.(1)

Characteristics Of Olfactory Neuroblastoma Tumor

Sometimes a tumor can be multi-focal when one lesion is located above the ethmoid plate, and the second below it, while even during microscopic analysis it is not possible to detect the connection between the two sites.

Localization of neuroblastoma at the level of the upper parts of the nasal cavity and the bottom of the anterior cranial fossa explains the early involvement of the sieve plate with germination in the cranial cavity. Sometimes metastases are found in the lymph nodes of the neck. Doctors can meet them both at the initial treatment of the patient, and many years later, after the treatment.

According to various reports, the frequency of metastases in the lymph nodes varies from 10 to 33% and distant metastases occur in 10-40% of cases. Most often, the lungs, brain, and bones are affected. The overall 5- and 10-year survival is usually higher than with other tumors of the upper parts of the nasal cavity, and is 80% and 50%, respectively. Regular endoscopic and MR monitoring of tumor growth is necessary since relapses and distant metastases can occur even 10 years after the onset of treatment.(2)

What Triggers Olfactory Neuroblastoma?

The mechanism of neuroblastoma is not yet clear. It is known that a tumor develops from embryonic neuroblasts, which at the time of the birth of the baby were not mature to nerve cells. The presence of embryonic neuroblasts in a newborn or young child does not necessarily lead to the formation of neuroblastoma – small areas of such cells are often detected in children under the age of 3 months. Subsequently, embryonic neuroblasts can transform into mature tissue or continue to divide and give rise to neuroblastoma.

A pathognomonic genetic defect in neuroblastoma is the loss of a portion of the short arm of the 1st chromosome. In a third of patients in the tumor cells, the expression or amplification of the N-myc oncogene is detected; such cases are considered prognostically unfavorable due to the rapid spread of the disease and the resistance of neoplasia to chemotherapy.

Microscopy of neuroblastoma reveals round small cells with dark-spotted nuclei. The presence of foci of calcification and hemorrhage in the tumor tissue is characteristic of these tumor cells.(3)

Neuroblastoma Classification

There are several classifications of neuroblastomas, tailored to the size and prevalence of the neoplasm. A common classification is:

Stage I – a single node is detected with a size of not more than 5 cm. There are no lymphomatous and hematogenous metastases.

Stage II – a single neoplasm is determined from 5 to 10 cm in size. There are no signs of damage to the lymph nodes and distant organs.

Stage III – a tumor is detected with a diameter of less than 10 cm with the involvement of regional lymph nodes but without damage to distant organs or a tumor with a diameter of more than 10 cm without damage to lymph nodes and distant organs.

Stage IVA – neoplasia of any size with distant metastases is determined. It is not possible to assess the involvement of lymph nodes.

Stage IVB – multiple neoplasms with synchronous growth are detected. The presence or absence of metastases in the lymph nodes and distant organs cannot be established.(3)

Surgery For Olfactory Neuroblastoma

The recommended treatment method is surgical. Depending on the location of the tumor and the experience of the surgeon, endoscopic endonasal access, lateral rhinotomy, craniofacial resection, a combination of endoscopic access with anterior craniotomy can be used.(1)(4)

References:

  1. Harvey RJ, Nalavenkata S, Sacks R, et al. Survival outcomes for stage‐matched endoscopic and open resection of olfactory neuroblastoma. Head & neck. 2017;39(12):2425-2432.
  2. Attwood JE, Jeyaretna DS, Sheerin F, Shah KA. Mixed Olfactory Neuroblastoma and Adenocarcinoma with In Situ Neuroendocrine Hyperplasia. Head and neck pathology. 2019:1-7.
  3. Uccella S, Ottini G, Facco C, et al. Neuroendocrine neoplasms of the head and neck and olfactory neuroblastoma. Diagnosis and classification. Pathologica. 2017;109(1):14-30.
  4. Wu J-Y, Chiou J-F, Ting L-L. Chemo-radiotherapy for olfactory neuroblastoma: cases report and literature review. 2019.

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