Case of Nasopharyngeal Neoplastic Lesion with Associated Perineural Spread

Perineural spread of disease in head and neck tumors is a well described phenomenon in surgical and imaging literature. Braches of trigeminal and facial nerve serve as the most common conduit for the process to occur. However features of nerve involvement are not unique to tumor spread alone. Opportunistic infections, inflammatory disorders and primary nerve tumors also exhibit similar imaging feature. Shahmeer Khan*, Zafar Sajjad and Fatima Mubarak Department of Radiology, Aga Khan University Hospital, Pakistan Figure 1: Axial T1 weighted images axial Section, showing abnormal hypointense Lesion (arrow) involving the left nasopharyngeal soft Tissue protruding into the nasopharyngeal Airway and the nasal cavity anteriorly. Annals of Clinical Case Reports Radiology Remedy Publications LLC. , | http://anncaserep.com/ 2019 | Volume 4 | Article 1676 2 Shahmeer Khan, et al., Imaging findings MRI brain with contrast examination findings: Axial T1 (Figure 1) image reveals a hypointense abnormal signal intensity lesion involving the left nasopharyngeal soft tissues which appears heterogeneously hyperintense on T2 weighted axial image (Figure 2). The lesion shows heterogeneous post contrast enhancement on T1 post contrast axial image (Figure 3). There is extension of the enhancement along the dura along the course of branches of trigeminal nerve up to the region of cavernous sinus (Figure 4). Figure 2: T2 weighted image through base of Skull hyper intense signals in the abnormal Lesion involving left nasopharyngeal soft Tissues (arrow). Figure 3: T1 post contrast image axial section shows heterogeneous enhancement within this lesion. Figure 4: T1 post contrast image axial section, reveals enhancement extending along the branches of trigeminal nerve (arrow) up to the region of cavernous sinus (curved arrow) , involving the dura (arrow head) , without intra axial extent. Figure 5: T1 weighted image sagittal section, shows nerve thickening along the course of mandibular division (arrow) of trigeminal nerve. Figure 6: T1 post contrast sagittal image reveals, abnormal thickening and enhancement along the course of maxillary (arrow) and mandibular (arrow head) divisions of trigeminal nerve with extension up to the Meckels cave (curved arrow). Figure 7: MIP and 8 fused images reveal abnormal FDG uptake in the lesion in nasopharyngeal soft tissues along with extension of the uptake along the branches of trigeminal nerve with intracranial extent. Coronal T1 pre and post contrast images reveal abnormal thickening and enhancement involving the maxillary and mandibular divisions of left trigeminal nerve. The lesion is extending anterioinferiorly to involve the hard palate (Figure 5). Over all findings are consistent with a neoplastic lesion involving the left nasopharyngeal soft tissues with perineural spread along branches of Vth nerve with intra dural extent, however no intra axial involvement. PET-CT scan findings: Coronal maximum intensity projection (Figure 6) and coronal fused images (Figure 7) show abnormal FDG uptake in the lesion involving the nasopharyngeal soft tissue with Annals of Clinical Case Reports Radiology Remedy Publications LLC. , | http://anncaserep.com/ 2019 | Volume 4 | Article 1676 3 Shahmeer Khan, et al., abnormal uptake along the course of maxillary and mandibular divisions of trigeminal nerve up to the region of Meckel’s cave. Discussion Perineural spread is a well recognized entity in surgical and imaging literature. Since squamous cell carcinoma is the most common head and neck tumor, it results in highest number of cases with perineural spread [2]. Typical imaging features of perineural tumor spread are nerve enhancement and thickening which are well recognized on MR imaging along with abnormal uptake on FDG pet scan however these features are not unique to tumor spread alone and can be seen in infective, inflammatory and primary nerve pathologies as well [5]. Most commonly involved conduits are the trigeminal (Figure 8) and facial nerves (Figure 9) and hence the knowledge of anatomy and coarses of these two structures is paramount to identification of the pathology [8]. Figure 8: Demonstrating the illustration of cranial nerve V and its major branches. Figure 9: Demonstrates illustration of course of cranial nerve VII. According to eighth edition of the TNM staging for head and neck tumors, perineural spread is an independent staging criteria irrespective of nodal status; hence it is important to recognize perineural spread as the entity comes with a worse prognosis compared to localized disease [9]. It also has therapeutic implications as tumors with perineural tumor spread would include wide would require wide field radiation, neoadjuvant chemotherapy along with surgical resection rather than resection alone for localized disease [1]. Conclusion It is important to screen and mention features of nerve involvement in head and neck tumors, as this has therapeutic and staging implications. References 1. Ong CK, Chong VH. Imaging of perineural spread in head and neck tumours. Cancer Imaging. 2010;10(1A):S92-S98. 2. Paes FM, Singer AD, Checkver AN, Palmquist RA, De La Vega G, Sidani C. Perineural spread in head and neck malignancies: clinical significance and evaluation with 18F-FDG PET/CT. Radiographics. 2013;33(6):171736. 3. Lian K, Bartlett E, Yu E. Perineural tumor spread along the sixth cranial nerve: CT and MR imaging. AJNR Am J Neuroradiol. 2013;32(9):E178. 4. Parsi K, Itgampalli RK, Vittal R, Kumar A. Perineural spread of rhinoorbito cerebral mucormycosis caused by Apophysomyces elegans. Ann Indian Acad Neurol. 2013;16(3):414-7. 5. Moreira MCS, Santos AC, Cintra MB. Perineural spread of malignant head and neck tumors: review of the literature and analysis of cases treated at a teaching hospital. Radiol Bras. 2017;50(5):323-7. 6. Lee KJ, Abemayor E, Sayre J, Bhuta S, Kirsch C. Determination of perineural invasion preoperatively on radiographic images. Otolaryngol Head Neck Surg. 2008;139(2):275-80. 7. Farasat S, Yu SS, Neel VA, Nehal KS, Lardaro T, Mihm MC, et al. A new American Joint Committee on Cancer staging system for cutaneous squamous cell carcinoma: creation and rationale for inclusion of tumor (T) characteristics. J Am Acad Dermatol. 2011;64(6):1051-9. 8. Jarnalo CM, Lycklama à Nijeholt G, Sanchez-Aliaga E, Castelijns JA, Amsterdam NL, Den Haag N. Patterns of perineural spread of head and neck malignancies. European Congress of Radiology. 2014;1-24. 9. Lydiatt WM, Patel SG, O'Sullivan B, Brandwein MS, Ridge JA, Migliacci JC, et al. Head and neck cancers-major changes in the American Joint Committee on cancer eighth edition cancer staging manual. CA Cancer J Clin. 2017;67(2):122-37.