A variety of neoplasms, derived from a multitude of tissue types, can develop in the sinonasal tract. Sinonasal neoplasms are classified as epithelial or mesenchymal. Epithelial tumors occur in the epithelial lining of the nasal and sinus cavities, accessory salivary tissue, neuroendocrine tissue, and the olfactory mucosa. Mesenchymal tumors are found in supporting tissues.