Olfactory neuroblastoma behavior inside and outside the olfactory cleft.

PURPOSE: Olfactory neuroblastoma (ONB) is a rare malignant tumor of the nose. The currently available evidence links this disease with cells of the olfactory epithelium. The detailed description of tumor site and its extension is the key of treatment. The aim of the present study was to describe the way ONB develops inside and outside the olfactory cleft. METHODS: Thirteen consecutive patients treated between 2004 and 2014 for ONB with unequivocal pathologic diagnosis, complete diagnostic imaging and endonasal endoscopy surgery were enrolled in this retrospective study. The site of origin and local extension of each tumor were studied in detail based on computed tomography/magnetic resonance imaging, surgical report, registered videotape of the surgery, and pathological reports. RESULTS: This series shows the behavior of a tumor arising either in the olfactory clefts (11 cases) or in the ethmoidal labyrinth (2 cases). When the setting begins with a tumor located in the olfactory cleft (below or in contact with the cribriform plate), the further step can be the extension to the ethmoidal labyrinth before intracranial or intraorbital extension. When tumors originate inside the ethmoidal labyrinths, the extension can first be into frontal sinus or orbital cavity. CONCLUSIONS: This fine anatomic and radiologic description shows the natural behavior of ONB inside and outside the olfactory cleft. As a consequence, the staging system developed by Kadish seems inadequate and Dulguerov's staging system could be improved. However, the preliminary proposed modification has to be evaluated in a prospective and large, multicenter cohort of patients.