Imaging of Nasal Cavity and Paranasal Sinus Tumors

Tumors of the nasal cavity and paranasal sinuses are uncommon neoplasms; however, radiological recognition of tumors is important due to frequent imaging of the paranasal sinuses. The nasal cavity is composed of widely diverse tissue types; therefore, it gives rise to a large histological variety of neoplasms. The World Health Organization (WHO) classification of the nasal cavity and paranasal sinuses comprises malignant and benign epithelial tumors, soft tissue tumors, tumors of bone and cartilage, hematolymphoid tumors, neuroectodermal tumors, germ cell tumors, and secondary tumors. Primary malignant tumors of the sinonasal cavities are most commonly of epithelial origin and approximately 80% of malignant tumors of the sinonasal cavity are squamous cell carcinoma (SCC). Although SCC of the nasal cavity can present at an early stage, those of the paranasal sinuses are often asymptomatic initially and are usually diagnosed at an advanced stage. Tumor involvement of the orbit, anterior skull base, pterygopalatine fossa, and/or masticator space is common at presentation. However, some benign tumors may also demonstrate aggressive growth into adjacent structures and appear similar to malignancies. Imaging plays an important role in the diagnosis and characterization of nasal cavity and paranasal sinus neoplasms. Although imaging appearances of these tumors are usually not specific and most of the time histological assessment is required for definitive diagnosis, certain tumors have characteristic features that are useful for radiological evaluation. Improvements in imaging technology, especially the introduction of multislice computed tomography (CT) and the use of magnetic resonance imaging (MRI) methods have led to better delineation and characterization of tumors. In this chapter, imaging of nasal cavity and paranasal sinus tumors is presented.