Olfactory Neuroblastoma.

Abstract

Olfactory neuroblastoma is a rare tumor. Nasal endoscopy typically identifies a soft mass arising from the olfactory cleft. Computer tomography and magnetic resonance imaging are mandatory for staging (in association with 18F-fluorodeoxyglucose positron emission tomography) in high-grade and/or high-stage tumors. Biopsy must be representative to confirm a diagnosis and for grading purposes. Two complementary classifications are described: one (Kadish) based on clinical-radiological analysis, and the other (Hyams) on histological criteria. Based on Hyams grading, studies have pointed out that grades III-IV entail significantly different behavior and prognosis. A multimodal approach, which may combine surgery, chemotherapy, and radiotherapy, is essential to manage these tumors. Treatment schedules which include surgery seem to be superior to others. Surgery classically consisted of anterior craniofacial resection to obtain good exposure. However, the role of transnasal endoscopic surgery has expanded because of its association with fewer complications, shorter hospital stays, and comparable oncologic results to the open surgical techniques. Unilateral endoscopic craniectomy can be performed for limited lesions to avoid definitive anosmia. Treatment that includes radio- and chemotherapy is recommended for advanced and high-grade tumors. The role of neoadjuvant chemotherapy in advanced-stage lesions is emerging. The main prognostic factors associated with poor patient outcome are Hyams grade III-IV, Kadish C-D, and positive surgical margins. Lifelong follow up is recommended.