Key points

Introduction

Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignant tumor of the nasal cavity first described by Berger and colleagues in 1924. These tumors have a propensity for local invasion into surrounding structures and distant metastases, most commonly to the neck, lungs, and bones.

Patients with ENB typically present with nonspecific chief complaints of nasal obstruction and epistaxis, and definitive diagnosis is made on biopsy. Histopathology is consistent with lobular architecture, small round blue cells in characteristic Homer-Wright pseudorosettes and Flexner-Wintersteiner rosettes, and prominent microvascularity ( Fig. 1 ). Hyams developed a histopathologic grading system classifying ENB into four groups, with poorer prognosis occurring with increasing grade from I to IV ( Table 1 ). Several attempts have been made to stage ENB based on imaging and surgical characteristics, with the most commonly used systems being developed by Kadish and coworkers, Dulguerov and Calcaterra, and Biller and coworkers, with a more recent modification of the Kadish system by Morita and coworkers ( Table 2 ).

Histopathologic sample of esthesioneuroblastoma. Note Homer-Wright rosettes ( arrowheads ) (H&E stain).

( Courtesy of Dr James J. Sciubba, Lutherville-Timonium, MD.)

Management of ENB is generally surgical, with evidence suggesting that surgery with adjuvant radiation may provide the best prognosis. Many surgical approaches have been described, including extracranial approaches, craniofacial resection, endoscopic-assisted craniofacial resection, and most recently purely endoscopic expanded endonasal resection. This article describes purely endoscopic surgical management of ENB and reviews outcomes of this approach described in the literature.

Introduction

Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignant tumor of the nasal cavity first described by Berger and colleagues in 1924. These tumors have a propensity for local invasion into surrounding structures and distant metastases, most commonly to the neck, lungs, and bones.

Patients with ENB typically present with nonspecific chief complaints of nasal obstruction and epistaxis, and definitive diagnosis is made on biopsy. Histopathology is consistent with lobular architecture, small round blue cells in characteristic Homer-Wright pseudorosettes and Flexner-Wintersteiner rosettes, and prominent microvascularity ( Fig. 1 ). Hyams developed a histopathologic grading system classifying ENB into four groups, with poorer prognosis occurring with increasing grade from I to IV ( Table 1 ). Several attempts have been made to stage ENB based on imaging and surgical characteristics, with the most commonly used systems being developed by Kadish and coworkers, Dulguerov and Calcaterra, and Biller and coworkers, with a more recent modification of the Kadish system by Morita and coworkers ( Table 2 ).

Histopathologic sample of esthesioneuroblastoma. Note Homer-Wright rosettes ( arrowheads ) (H&E stain).

( Courtesy of Dr James J. Sciubba, Lutherville-Timonium, MD.)

Management of ENB is generally surgical, with evidence suggesting that surgery with adjuvant radiation may provide the best prognosis. Many surgical approaches have been described, including extracranial approaches, craniofacial resection, endoscopic-assisted craniofacial resection, and most recently purely endoscopic expanded endonasal resection. This article describes purely endoscopic surgical management of ENB and reviews outcomes of this approach described in the literature.

Treatment goals and planned outcomes

Like other malignant sinonasal tumors, treatment goals and expected outcomes depend on extent of disease and tumor grade at presentation. Overall 5- and 10-year survival rates based on Surveillance, Epidemiology, and End Results tumor registry data were 62.1% and 45.6%. In the original report by Kadish and coworkers of 17 patients with ENB, 100% of patients with group A disease (seven of seven), 80% (four of five) with group B disease, and 40% (two of five) with group C disease survived 3 or more years. A more recent study showed 2-year survival of 75% (six of eight) in patients with group A or B disease versus 29% (5 of 17) in those with group C disease. Another study showed high Hyams grade as a poor prognostic indicator with median survival of 9.8 years in low-grade tumors (grade I or II) and 6.9 years in high-grade tumors (III or IV). The goal of treatment of ENB is complete surgical resection with negative margins. However, the treatment plan should be individualized for each patient. In cases where a negative margin is unattainable or returns positive postoperatively, or in those cases with positive nodal or distant metastases, adjuvant radiation and chemotherapy should be discussed. In advanced cases where cure is unlikely, the surgeon must have an honest discussion with the patient and his or her family regarding goals of care and palliative care.

Preoperative planning and preparation

Preoperative planning begins with comprehensive history and physical by the neurosurgeon and the otolaryngologist–head and neck surgeon. Special emphasis must be placed on any factors that could increase the difficulty of the case, such as a history of chronic rhinosinusitis and previous functional endoscopic sinus surgery. As in all surgical patients, preoperative clearance must be performed by the appropriate internist and/or anesthesiologist to ensure that the patient can safely undergo general anesthesia.

A complete physical examination with special attention to the head and neck must also be performed. Findings of interest include signs of advanced disease, such as cranial nerve deficits or proptosis, and evidence of cervical lymphadenopathy. The examination should conclude with careful nasal endoscopy ( Fig. 2 ) with particular attention to anatomic variants that could reduce endoscopic access, including septal deviation or spurs, turbinate hypertrophy, or conchae bullosa.

Endoscopic appearance of left nasal cavity ENB.

Preoperative imaging is essential to determining not only the extent of disease but also the ability to obtain a negative surgical margin. Imaging should also guide the surgeon’s choice of open versus endoscopic approaches. In general, those patients with disease extent lateral to the meridian of the orbit, with significant intraorbital or intracranial involvement, and/or those with involvement of the facial soft tissues should be offered a traditional craniofacial resection rather than an expanded endonasal approach. Ultimately, careful preoperative evaluation and surgeon experience should guide the choice of surgical approach that is most likely to yield negative margins in the safest and least invasive manner possible. Complete preoperative imaging should include high-resolution computed tomography (CT) and MRI ( Fig. 3 ) with intraoperative image guidance protocols. A PET scan should also be performed to assess for occult regional and metastatic disease.

( A ) Coronal CT scan of left nasal ENB. ( B ) Coronal MRI of left nasal ENB.

Patient positioning

The patient is placed in the supine position and the head secured using a Mayfield three-point head fixator. The neck is placed in extension with slight rotation toward the surgeons. The video monitor is placed on the patient’s left, across from the surgeons and monitors for both intraoperative CT and MRI navigation are placed adjacent to the video monitor. Care is taken to secure essential equipment including the nasal endoscope, suction tubing, suction monopolar electrocautery, pistol-grip bipolar electrocautery, tissue shaver, and drill in a manner that it is easily accessible to the surgeons. Foot pedals are placed side by side at the surgeons’ feet. Once proper set up and functioning of all instrumentation is confirmed, the patient is registered to the neuronavigation systems and the nasal cavity is irrigated with clindamycin solution. Perioperative antibiotics are administered and a time-out procedure is performed in anticipation of beginning the case. Surgical resection is performed with an endoscopic sinus and neurosurgeon team using a two-surgeon, three- to four-handed technique.