A malignant olfactory Neuroblastoma arising from the olfactory Epithelium of the superior Nasal Cavity and cribriform plate. It is uncommon (3% of nasal Tumors) and rarely is associated with the production of excess Hormones (e.g., SIADH, Cushing Syndrome). It has a high propensity for multiple local Recurrences and bony Metastases. (From Holland et al., Cancer Medicine, 3rd ed, p1245; J Laryngol Otol 1998 Jul;112(7):628-33)