Sinonasal Neoplasms Mohit Agarwal, MD,* and Bruno Policeni, MD† Introduction benign lesions will usually cause bone remodeling and/or scle- rosis. Loss of bright fat marrow intensity on T1W MR images f Rip Van Winkle went to medical school during the 80s is a sign of bone involvement. Differentiation of benign vs I and woke up today among a meeting of pathologists, he malignant lesions remains a challenge with imaging and excep- would think he was on a different planet and listening to an tions to the previously mentioned features exist. Pathology is “ ” alien language. The once pink and purple world of pathol- required to determine the diagnosis in the majority of cases.7 ogy is now extensively multicolored with an overwhelming Imaging has more to offer than just histological diagnosis, number of immunostains and molecular markers. Histologi- the most important of which is tumor mapping. It must be cal diagnoses now come with an alphanumeric tail, each determined if the tumor is confined within a single sinus or implying the unique gene expression associated with that if there is extension into surrounding structures. Tumors of tumor entity. Needless to say, similar things have happened the maxillary sinuses can extend to the anterior ethmoid fi to the new fourth edition WHO classi cation of sinonasal sinus, nasal cavity, and orbit. Anterior ethmoid tumors can fi (SN) neoplasms, where SMARC B1-de cient carcinoma, involve the frontal sinuses and the nasal cavity. Nasal cavity Nuclear protein testis (NUT) midline carcinoma, and human tumors commonly involve the ethmoid sinus. Posterior eth- papilloma virus (HPV)-related multiphenotypic SN carci- moid tumors tend to involve the sphenoid sinus.7 1 noma have found a place. Intracranial extension is a dreaded complication, more In the following description of SN neoplasms, we will dis- commonly seen with ethmoid, sphenoid, and frontal sinus cuss benign and malignant tumors affecting the nasal cavity tumors. Images must be carefully evaluated to look for intra- and paranasal sinuses, with reference to the new entities cranial disease including dural and parenchymal involvement. fi 2,3 included in the latest WHO classi cation (Tables 1 and 2). It may be difficult to confirm dural invasion if the thickening and enhancement is linear. Nodular thickening and enhance- ment is more indicative of tumor invasion. Abnormal signal/ Imaging of SN Neoplasms enhancement within the adjacent brain parenchyma is highly Imaging differentiation of SN tumors can be difficult. Despite suggestive of tumor invasion. A detailed description of bony this, it remains a goal of the interpreting radiologist to ascertain involvement at the skull base will help in planning the surgical if the tumor in question is benign or malignant. Well-defined approach and prevent untoward postoperative complications fl margins, involvement of a single sinus, homogeneous, low such as cerebrospinal uid (CSF) leak. attenuation on CT, and high long TR signal on MR are imaging Orbital extension also worsens prognosis and must be fi identified for optimal treatment planning as orbital exentera- features suggestive of benignity. Irregular in ltrating margins, 6 bone involvement, extension beyond the sinus walls, high CT tion may be necessary. Malignant tumors of the maxillary attenuation, and hypointense signal on long TR MR sequences antrum are most likely to involve the orbits via superior are imaging features that raise concern for a malignant pro- extension. Ethmoid sinus tumors may also extend to the cess.4-6 The status of the bone adjacent to the tumor can give orbits by mere proximity. Posterior ethmoid and spheno- useful clues to the nature of the tumor. In general, destructive ethmoid tumors can invade the orbital apex. bone erosion and fragmentation are signs of malignancy, while Involvement of the bony palate may alter the surgical course and may herald development of oro-nasal or oro-antral fistu- *Department of Radiology, Division of Neuroradiology, Medical College of las. Involvement of the pterygopalatine fossa (PPF) is an Wisconsin, Milwaukee, WI. important imaging finding when mapping SN neoplasms as it y Department of Radiology, Division of Neuroradiology, University of Iowa, is suggestive of perineural tumor spread, an ominous features Iowa City, IA. of SN neoplasms. A rich plexus of nerves traverses the PPF Acknowledgments: The authors would like to acknowledge Michelle A. and perineural tumor may extend in an antegrade fashion to Michel, MD for her contribution of images to this manuscript. Address reprint requests to Mohit Agarwal MD, 8701 Watertown plank involve the peripheral V2 branches or in a retrograde fashion road, Milwaukee, WI 53226. E-mail: [email protected] to involve the main trunks of the trigeminal nerve. Even in the 244 https://doi.org/10.1053/j.ro.2019.03.001 0037-198X/© 2019 Elsevier Inc. All rights reserved. Sinonasal Neoplasms 245 6 Table 1 WHO Classification of Tumors of the Nasal Cavity, involved sinuses. Unless inspissated or complicated by hem- Paranasal Sinuses and Skull Base orrhage or high protein content, retained secretions have a Carcinomas high signal on long TR-weighted images in contrast to hyper- Squamous cell carcinoma cellular low signal tumor. Keratinizing, non-keratinizing and spindle cell MRI has greater soft tissue distinction compared to CT and Lymphoepithelial carcinoma remains the modality of choice for accurate tumor mapping Sinonasal undifferentiated carcinoma and surveillance after treatment.6,8 Orbital and intracranial NUT carcinoma tumor extension are more accurately assessed with MRI. Bone Neuroendocrine carcinomas destruction, erosion, and remodeling are better assessed on Small cell and large cell CT, but MRI again proves superior if bone marrow involve- Adenocarcinomas ment is of concern. MRI is far superior to CT for diagnosing Intestinal-type and non-intestinal type perineural tumor spread. Nodal and distant metastases are Teratocarcinosarcoma best assessed by FDG-PET.9 With regards to the MRI tech- Sinonasal papillomas fi Inverted, oncocytic and exophytic nique, thin section (3-4 mm) small eld of view (FOV) Respiratory epithelial lesions (16-18 mm) short-tau inversion recovery (STIR), precontrast Respiratory epithelial adenomatoid hamartoma (REAH) T1W and postcontrast T1W images in at least 2 planes (axial Seromucinous hamartoma and coronal) provide adequate information in most cases. Use Salivary gland tumors of fat suppression on postcontrast images is necessary to eval- Malignant soft tissue tumors uate the abnormal enhancement. A whole-brain FLAIR Fibrosarcoma sequence is optional, but is useful in the evaluation of the Undifferentiated pleomorphic sarcoma brain parenchyma. If used as a supplement to MRI, CT can be Leiomyosarcoma performed without contrast to assess bony involvement. If Rhabdomyosarcoma MRI is contraindicated, CT with contrast can be performed NOS, Embryonal, Alveolar, Pleomorphic, spindle cell for tumor mapping using thin sections (1 mm) and multipla- Angiosarcoma Malignant peripheral nerve sheath tumor nar reformats. Biphenotypic sinonasal sarcoma Quantitative diffusion techniques have been found useful in Synovial sarcoma differentiating benign from malignant tumors, where malig- Borderline/low-grade malignant soft tissue tumors nant tumors have lower apparent diffusion coefficient (ADC) Benign soft tissue tumors values compared to benign processes.10-16 Diffusion weighted Leiomyoma imaging (DWI) and ADC have also been studied to differenti- Hemangioma ate different tumor types and have revealed overall lower ADC Schwannoma values for lymphomas compared to squamous cell carcinoma Neurofibroma (SCC).10,14 Advanced imaging techniques such as MR perfu- Other tumors sion are being investigated for their potential use and encour- Meningioma aging preliminary data have been obtained. Time-intensity Sinonasal ameloblastoma Chondromesenchymal hamartoma curves (TIC) are plotted for dynamic contrast-enhanced MRI Hematolymphoid tumors to look for maximum (Tmax) and peak enhancement (Tpeak). Extranodal NK/T-cell lymphoma A “persistent” TIC suggests a benign process, while a “wash- 12,17 Extraosseus plasmacytoma out” TIC suggests a malignant tumor. Neuroectodermal/melanocytic tumors Ewing sarcoma/PNET Olfactory neuroblastoma Mucosal melanoma Clinical Features Approximately 3% of head and neck malignancies arise in the SN region.6 This compromises 0.2%-0.8% of all malig- absence of PPF involvement, perineural tumor should be pro- 6 actively assessed with a thorough inspection of the normal fat nancies, a low number. Despite their rare occurrence, they fi pads at the neural foramina and identification of abnormal are clinically signi cant due to the grim prognosis. By the enhancement along the course of the nerves. time of presentation, the tumors are typically advanced, fur- Tumor growth commonly occludes the sinus drainage ther complicating the treatment in an anatomic location pathways and a frequent problem during tumor mapping is fraught with concerns of postoperative dysfunction and differentiating tumor from retained secretions within the cosmesis. Symptoms are usually vague and overlap with those of sinusitis and dental infection. Common symptoms fi Table 2 Emerging Sinonasal Neoplasms including nasal stuf ness, headache, and vague orbital pain may not always prompt an imaging investigation, further SMARCB1 (INI-1) deficient sinonasal carcinoma delaying diagnosis. Obvious signs of a mass such as propto- HPV-related sinonasal carcinoma sis, epistaxis, or