An atypical Esthesioneuroblastoma of the sphenoid sinus: a case report
Authors: Touihmi Safaa , Horrane Ichraq , Rkain Ilham 
Published: April 2023

Introduction and importance:
Esthesioneuroblastoma (ENB) is a rare tumor, arising from the olfactory epithelium. It manifests as an aggressive tumor in the superior aspect of the nasal cavity. Sinonasal symptoms are the most common. The cervical lymph nodes ensue in nearly 10% of cases and hematogenous metastases are rare. The diagnosis is histological. This tumor is staged using the Kadish et al System. The imaging techniques, using both computed tomography (CT) and MRI provides all the important information required for treatment modality. Today, the standard multimodal treatment combining external craniofacial resection, radiotherapy, and chemotherapy has improved long-term survival.

Case presentation:
A 27-year-old male patient with no medical history, complained of a headache, a unilateral right nasal obstruction, epistaxis, and anosmia for 2 months. Nasal endoscopy showed a pinkish-gray mass filling the right nasal cavity. An enhanced-contrast CT scan was performed and objectified a mildly enhancing extensive mass of the sphenoid sinus with bone erosion of the left wall of the sinus and intracranial involvement. An intranasal biopsy was performed, resulting in a histopathological diagnosis of olfactory neuroblastoma. Our case was staged as stage C according to the Kadish staging. The tumor was inoperable, the patient had chemotherapy, radiotherapy, and pain management.

Clinical discussion:
ENB is an aggressive malignant tumor derived from the specialized olfactory neuroepithelium of the upper nasal cavity. Several published reports confirm ectopic cases of ENB throughout the nasal cavity and the central nervous system. Because sinonasal malignant lesions are rare and difficult to distinguish from their benign counterparts. ENBs appears as a soft, glistening, polypoidal, or nodular mass covered by intact mucosa or as friable masses with ulceration and granulation tissue. A radiological, CT scan through the skull base and paranasal sinuses with intravenous contrast should be performed. ENBs are solid, enhancing nasal cavity masses that may manifest erosion into nearby osseous. MRI provides better discrimination between tumor and secretions and optimal assessment of orbital, intracranial, or brain parenchymal involvement. The biopsy is the next important step in securing a diagnosis. Classic treatment strategies of ENB are based on surgery or radiotherapy as unique modalities or a combination of surgery and radiation therapy. More recently, chemotherapy has been introduced in the therapeutic armamentarium since ENB has proven to be chemosensitive. The elective neck dissection remains controversial. Long-term follow-up is mandatory for patients with ENB.

Conclusion:
While most ENBs originate in the superior nasal vault and present with typical symptoms of nasal obstruction and epistaxis in the late stages of the disease, uncommon manifestations should be considered as well. Adjuvant therapy should be considered in patients with advanced disease and unresectable disease. A continuing follow-up period is needed.