IMAGING IN ORAL AND OROPHARYNGEAL CANCERS 19/2/2022 ORAL CAVITY CANCERS • SCC m/c - 90% of malignant tumors of oral cavity and oropharynx. • Others include minor salivary gland tumors, lymphomas. • Tumors of oral cavity less aggressive – squamous epithelium derived from ectoderm. • Tumors of oropharynx more aggressive – squamuos epithelium derived from endoderm. Oral cavity anatomic sub divisions • • • • • • • Lips Floor of the mouth Oral tongue Buccal mucosa Upper and lower gingivae Hard palate Retromolar trigone • In the order of frequency Lip,oral tounge and FOM are m/c sites for SCC of oral cavity • Key features that should be sought in SCC of the lip include osseous invasion and lymphatic involvement. • Lymphatic spread is primarily through level I and II lymph nodes. • Osseous involvement usually occurs along the buccal surface of maxillary or mandibular alveolar ridge • Crossing midline precludes partial glossectomy. • Involvement of the mylohyoid muscle may be directly depicted on coronal images • . A finding of mandibular bone invasion mandates an assessment of the inferior alveolar nerve. • The tumor may spread to sites posterior to the mandibular ramus, the masticator space, the superior constrictor muscles, and the mandibular branch of the trigeminal nerve. • Anterior spread occurs along the alveolar ridge, and inferior spread occurs along the mandible and inferior alveolar nerve. • The tumor also may spread along the pterygomandibular raphe, a thick facial band that extends between the posterior border of the mandibular mylohyoid ridge and the hamulus of the medial pterygoid plate. • The pterygomandibular raphe provides access to the masticator space superolaterally and the floor of the mouth inferomedially. OROPHARYNX CANCERS • Base of the tongue • Tonsils TONGUE BASE • Detection of SCC in base of the tounge challenging due to dense musculature , lack of fat planes and variability in the size of the lingual tonsils. • Evaluation includes: • • • • • • (a) submucosal involvement (b) involvement of the intrinsic muscles of the tongue (c) crossing of the midline of the tongue (d) invasion of the pre-epi glottic fat (e) osseous involvement (f) cervical lymphatic spread. • SCCs of the tongue base often originate on one side and spread laterally to the tonsillar pillars, anteriorly to the sublingual space, or posteriorly under the valleculae. • Posterior and inferior extension important, because involvement of the larynx precludes the surgical option of partial glossectomy. • Invasion of the pre-epi glottic space indicative of extension into the larynx,best depicted on T1-weighted axial and sagittal MR images. • If the tumor crosses the midline, relation to the contralateral neurovascular bundle must be determined, because partial glossectomy requires the preservation of one lingual artery and one hypoglossal nerve. TONSIL • Tonsillar subsites include the anterior and posterior tonsillar pillars and the palatine tonsils. • Tumor may spread into the nasopharynx, parapharyngeal space, masticator space, skull base, and tongue base. • • Most SCCs originate in the anterior tonsillar pillar,spread superiorly along the palate glossus to the hard and soft palates. From there along the tensor and levator palatine muscles. • Tonsillar SCCs also may spread upward to the nasopharynx . Anterior and medial along the superior constrictor muscles to the pterygomandibular raphe to the skull base and cranial nerves,posteriorly to the retropharyngeal or carotid space or inferiorly to the tongue base. • Evaluation includes: • (a) submucosal extension • (b) involvement of the pterygoid muscles • (c) extension along the pterygo mandibular raphe to the skull base • (d) osseous involvement • (e) involvement of the cervical lymph nodes. Routes of spread • 1. Direct extension • 2. Lymphatic pathways • 3.Neurovascular bundles 1. Direct extension • Osseous involvement - T4 • MR- replacement of T1 high marrow with intermediate signal, enhancing nerve. • Precludes widelocal excision,Treatment – Mandibulectomy/ maxillectomy 2. Lymphatic dissemination • Nodal involvement is the single most important prognostic indicator • Oral cavity -level I and II lymph nodes, Oropharynx levels II and III, and retropharyngeal nodes. • Retromolar trigone and FOM SCC show a strong predilection for lymphatic involvement 50%, Oral tongue 40% , Lip 10%, Hard palate in 10%–25% of cases. • Usual size criterion for pathology is a maximal longitudinal diameter of more than 15 mm for jugulodigastric lymph nodes and more than 10 mm for other nodes (except retropharyngeal lymph nodes- 8 mm). • Minimal axial diameter of 11 mm for jugulo digastric (level II) nodes and 10 mm for other nodes. • Normal nodes - reniform, pathologic – round, necrotic. • Extracapsular spread include high signal intensity in tissues surrounding a node, a poorly defined nodal border, irregular rim like enhancement of a node, and large nodal size. 3.5 times increased recurrence. 3. Neurovascular spread • Vascular invasion - increased nodal involvement - single most important prognostic indicator. • Peri neural spread is more common in floor of the mouth. • Features of perineural spread include foraminal enlargement and replacement of normal fat within the neural foramen. The nerve may appear enlarged on contrast-enhanced MR images. • perineural, lymphatic, or vascular invasion at pathologic analysis necessitate postoperative adjuvant radiation therapy AJCC 8TH EDITION AJCC 8TH EDITION References: • Arya S, Chaukar D, Pai P. Imaging in oral cancers. Indian J Radiol Imaging. 2012;22(3):195-208. doi:10.4103/0971-3026.107182 • Oral Cavity and Oropharyngeal Squamous Cell Cancer: Key Imaging Findings for Staging and Treatment Planning • Brian M. Trotta, Clinton S. Pease, Jk John Rasamny, Prashant Raghavan, and Sugoto Mukherjee • RadioGraphics 2011 31:2, 339-354 • Advances in Diagnosis and Multidisciplinary Management of Oropharyngeal Squamous Cell Carcinoma: State of the Art • Upendra Parvathaneni, Pierre Lavertu, Michael K. Gibson, and Christine M. Glastonbury • RadioGraphics 2019 39:7, 2055-2068 • https://headandneckrad.com/aerodigestive-tract • https://www.youtube.com/watch?v=KHu4JD3jx-w • https://www.youtube.com/watch?v=mWSIv6m3t-I THANK YOU!
