Observing a brain scan

Olfactory Neuroblastoma (Esthesioneuroblastomas)

Minimally invasive endonasel endoscopic surgery is now possible for most Olfactory Neuroblastomas

Olfactory neuroblastomas (esthesioneuroblastomas) arise from the olfactory nerves in the skull base and nasal cavity.

The optimal treatment for most patients with olfactory neuroblastomas (ONB) is maximal surgical removal followed by radiation and in some instances chemotherapy. Fortunately, for most patients with ONB, surgery can be performed via the nose using an endoscopic endonasal approach, although some large ONBs require a combined endonasal and trans-cranial approach.  At Pacific BTC, we have large experience in treating olfactory neuroblastomas and related sino-nasal tumors.

By incorporating cutting edge technology and instrumentation with proven surgical experience, we make surgery for ONBs and related skull base tumors safer, less invasive and more effective. Our neurosurgeons work closely with our radiation oncologists, neuro-oncologists and neuropathologists to design the optimal treatment plan that incorporates the latest in radiotherapy techniques and tumor biomarker studies.

By using comprehensive tumor histological subtyping and genomic sequencing, we are able to provide a personalized therapeutic approach for each patient with ONB.

Learn more about our multidisciplinary team


Olfactory neuroblastomas (ONBs) are rare malignant tumors that arise from the olfactory nerve (sense of smell) and extend into the nasal cavity. They are locally invasive tumors that grow into the ethmoid and other air sinuses and can extend onto the orbits as well as the brain.

In cases with intracranial (brain) extension, the tumor typically grows through the anterior skull base dura in the area of the cribiform plate and into the brain cavity elevating or infiltrating the frontal lobes. They occur equally in adult men and women and are uncommon in adolescents. Spread of disease to local lymph nodes and distant metastases occur in some patients. The most commonly used grading system for esthesioneuroblastoma is the Kadish system which includes grades A, B and C:

  • A. Nasal cavity only,
  • B. Nasal and paranasal sinus involvement,
  • C. Extension beyond nasal and paranasal sinus with intracranial, orbital, lymph node or distant metastases.


Olfactory neuroblastomas typically cause loss of sense of smell (anosmia), epistaxis (nasal bleeding), nasal congestion/obstruction, vision loss and headache. If the tumor invades the dura and intracranial space, seizures and/or cognitive changes may occur.


Olfactory neuroblastomas are typically diagnosed by magnetic resonance imaging (MRI) or computer tomography (CT) scans of the brain and paranasal sinuses.

For large, highly vascular tumors, pre-operative angiography and tumor embolization is often indicated.


The aggressive nature of ONB typically warrants multimodality treatment including surgical removal and radiotherapy in most cases and sometimes chemotherapy. Traditionally, most Stage C tumors (with cribiform plate and intradural involvement) were treated with a craniofacial surgical approach involving a transnasal approach and a frontal craniotomy.

However with advances in endoscopy, instrumentation and anatomical understanding, many if not most olfactory neuroblastomas can now be removed via an Endoscopic Endonasal Approach, including those with intradural extension. For some very large tumors with intracranial extension, a combined cranio-facial approach may still be needed.

After maximal surgical resection, focused radiosurgery or radiotherapy and chemotherapy is often indicated. Given advances in personalized and targeted genomic-based therapies, we routinely bank tissue for genetic analysis and detailed tumor biomarker studies. Having such critical biomarker data opens the door for novel therapies and ongoing or future clinical trials. Learn more about our tumor genetic sequencing capabilities.

Doctors and Specialists Who Treat Olfactory Neuroblastoma

Written and reviewed by:
We are a highly specialized team of medical professionals with extensive neurological and cranial disorder knowledge, expertise and writing experience.
Last updated: January 12, 2023