Neoplasms of the Oral Cavity 103 6 Neoplasms of the Oral Cavity Marc Keberle CONTENTS regions laterally, the circumvallate papillae and the anterior tonsillar pillar dorsally, and the hard palate 103 6.1 Anatomy cranially. The center of the oral cavity is fi lled out by 6.1.1 The Floor of the Mouth 103 6.1.2 The Tongue 103 the tongue. 6.1.3 The Lips and Gingivobuccal Regions 104 6.1.4 The Hard Palate and the Region of the Retromolar Trigone 105 6.1.1 107 6.1.5 Lymphatic Drainage The Floor of the Mouth 6.2 Preferred Imaging Modalities 107 6.3 Pathology 107 6.3.1 Benign Lesions 107 The fl oor of the mouth is considered the space be- 6.3.1.1 Congenital Lesions 107 tween the mylohyoid muscle and the caudal mucosa 6.3.1.2 Infl ammatory Conditions 111 of the oral cavity. The mylohyoid muscle has the form 112 6.3.1.3 Benign Tumors of a hammock which is attached to the mandible ven- 6.3.2 Squamous Cell Cancer 114 6.3.2.1 General Considerations 114 trally and laterally on both sides but with a free dorsal 6.3.2.2 Lip Cancer 117 margin. Coronal planes nicely demonstrate the anat- 6.3.2.3 Floor of the Mouth Cancer 117 omy of the mylohyoid as well as the geniohyoid mus- 6.3.2.4 Retromolar Trigone Cancer 118 cles (Figs. 6.4, 6.5). The geniohyoid muscles are paired 119 6.3.2.5 Tongue Cancer sagittally orientated slender muscles on the superior 6.3.2.6 Hard Palate, Gingival and Buccal Cancer 120 6.3.3 Other Malignant Tumors 122 surface of the mylohyoid muscle. In the median, they 6.3.3.1 Adenoid Cystic Carcinoma 122 arise from the inner surface of the mandible and pass 6.3.3.2 Mucoepidermoid Carcinoma 123 dorsally to insert onto the anterior surface of the 6.3.3.3 Miscellaneous (see also Table 6.1) 123 hyoid bone. Above these muscular landmarks is the 123 6.3.4 Recurrent Cancer primarily fat-fi lled bilateral sublingual space. It com- References 126 prises the following important paired structures: the sublingual gland, the hyoglossus muscle, the lingual artery, vein, and nerve, Wharton’s (submandibular) 6.1 duct, and dorsally the tip of the submandibular gland Anatomy as it surrounds the dorsal margin of the mylohyoid muscle. Anatomically noteworthy is that in the sagit- Predominantly, oral cavity lesions are clinically ap- tal plane the hyoglossus muscle separates Wharton’s parent. Except for important information on the dif- duct and the hypoglossal and lingual nerves, which ferential diagnosis, cross-sectional imaging provides course laterally, from the lingual artery and vein, the clinician with the crucial pretherapeutic infor- which lie medially (compare Figs. 6.1 and 6.5). mation on deep tumor infi ltration. In this regard, the clinician needs to know exactly which anatomic structures (Figs. 6.1–6.6) are involved. 6.1.2 The oral cavity is the most anterior part of the The Tongue aerodigestive tract. Its borders are the lips ventrally, the mylohyoid muscle caudally, the gingivobuccal While the posterior third of the tongue – located dorsally of the circumvallate papillae – forms part M. Keberle, MD of the oropharynx, the two anterior thirds of the Diagnostic Radiology, Medizinische Hochschule Hannover, tongue belong to the oral cavity. The tongue contains Carl-Neuberg-Str. 1, 30625 Hannover, Germany a complex mixture of various intrinsic and extrinsic 104 M. Keberle a b Fig. 6.1a,b. Axial CT (a) and MRI (b) of the fl oor of the mouth. 1, geniohyoid muscle; 2, mylohyoid muscle; 3, fatty lingual septum; 4, submandibular gland; 5, base of the tongue; 6, mandible; 7, hyoglossus muscle; arrows, sublingual (fat) space with lingual artery and vein a b Fig. 6.2a,b. Axial CT (a) and MRI (b) at the level of the tongue. 1, tongue with fatty lingual septum; 2, (lower) lip; 3, palatopha- ryngeal muscles and palatopharyngeal arch; 4, intrinsic lingual muscles fi bers; 5, parapharyngeal fat space; 6, medial pterygoid muscle; 7, masseter muscle; 8, mandible muscles. Intrinsic muscles are made up by longitudi- the (V3) mandibular nerve (Fig. 6.6). The tongue is nal, transverse, vertical, and oblique fi bers which are sagittally divided in two halves by a fatty midline not connected with any structure outside the tongue septum (Figs. 6.1–6.5). (Figs. 6.2, 6.4, and 6.5). The extrinsic muscles have their origin external to the tongue (Figs. 6.1 and 6.4): the genioglossus (chin), hyoglossus (hyoid bone), and 6.1.3 styloglossus (styloid process) muscles. Both intrinsic The Lips and Gingivobuccal Regions and extrinsic muscles of the tongue receive their in- nervation from the (XII) hypoglossus nerve. Sensory Externally, the lips are covered by keratinizing strati- fi bers are carried by the lingual nerve, a branch of fi ed squamous epithelium, and internally, by nonke- Neoplasms of the Oral Cavity 105 a b Fig. 6.3a,b. Axial CT (a) and MRI (b) at the level of the maxilla. 1, maxilla; 2, mandible; 3, lateral pterygoid muscle; 4, soft palate; 5, tongue; 6, parapharyngeal fat space; 7, masseter muscle; 8, buccinator muscle; 9, area of the retromolar trigone (with bony pterygoid process on CT); arrows, (Stensen’s) parotid duct a b Fig. 6.4a,b. Coronal CT (a) and MRI (b) at more anterior aspects of the oral cavity. 1, mandible; 2, (maxillary) hard palate with a tiny nerval canal; 3, mylohyoid muscle; 4, anterior belly of digastric muscle; 5, geniohyoid muscle; 6, genioglossus muscle; 7, intrinsic lingual muscles; 8, submandibular fat space; arrows, sublingual fat space with lingual artery and vein ratinizing stratifi ed squamous mucosa. The vestibule 6.1.4 of the mouth separates lips and cheeks from the al- The Hard Palate and the Region veolar processes of the mandible and maxilla. The of the Retromolar Trigone gingiva is the mucosa on both the lingual and the buccal aspects of the alveolar processes. The junction While the soft palate is part of the oropharynx, the of the gingival with the buccal mucosa is called gingi- mucosal layer beneath the hard palate belongs to the vobuccal region. At the level of the second maxillary oral cavity. There are several openings for palatine molar tooth Stensens’ (parotid) duct opens within the nerves piercing the hard palate (compare Figs. 6.4 buccal mucosa (Fig. 6.3). Moreover, minor salivary and 6.6). The strategic region posterior to the last glands are relatively frequent in the gingivobuccal maxillary molar tooth is called the retromolar trigone regions. Dorsally, the vestibules open into the dorsal (Fig. 6.3). The retromolar trigone has a connection to part of the oral cavity. the buccinator space laterally, to the anterior tonsillar 106 M. Keberle a b Fig. 6.5a,b. Coronal CT (a) and MRI (b) at more posterior aspects of the oral cavity. 1, mandible; 2, mylohyoid muscle; 3, hyoglos- sus muscle; 4, sublingual fat space (with lingual artery and vein); 5, soft (on CT) and hard (on MRI) palate; 6, submandibular fat space; 7, medial pterygoid process; 8, lateral pterygoid process; arrow, fatty lingual septum a b Fig. 6.6a,b. Anatomic views of the trigeminal nerve (from Bergman and Afi fi 2002, with permission). a a, Greater wing of the sphenoid bone; b, zygomatic bone; c, maxilla; d, mandible; e, petrous part of temporal bone; f, mastoid process; g, tongue; h, submandibular gland; i, sublingual gland; k, medial pterygoid muscle, l, lateral pterygoid muscle; m, genioglossus muscle; n, hyoglossus muscle. 1, internal carotid artery; 2, trigeminal nerve; 3, trigeminal ganglion; 4, trigeminal nerve (V/1, ophthalmic division); 5, trigeminal nerve (V/2, maxillary division); 6, trigeminal nerve (V/3, mandibular division); 7, facial nerve; 8, great superfi cial petrosal nerve; 9, inferior alveolar nerve; 10, mental nerve; 11, mylohyoid nerve; 12, anterior auricular nerve (with middle meningeal artery); 13, lingual nerve; 14, submandibular ganglion; 15, deep temporal nerve; 16, buccinator nerve; 17, chorda tympani; 18, internal carotid plexus (sympathetic nerves). b a, Frontal bone (frontal sinus); b, roof of the orbit (frontal bone); c, ocular bulb; d, M. levator palpbrae superioris; e, M. ocular superior rectus; f, M. ocular inferior rectus; g, wall of the nasal cavity; h, pterygoid process; i, sphenopalatine foramen; k, hard palate; l, pterygopalatine canal; m, mandible; n, medial pterygoid muscle; o, tympanic membrane (with an auditory bone). 1, maxillary artery; 2, optic nerve; 3, trigeminal nerve with trigeminal ganglion; 4, trigeminal nerve (V/1, ophthalmic division); 5, trigeminal nerve (V/2, maxillary division); 6, trigeminal nerve (V/3, mandibular division); 7, frontal nerve; 8, nasal nerve; 9, ethmoidal nerve; 10, ciliary ganglion; 11, ciliary ganglion, short ciliary nerves; 12, ciliary ganglion, long ciliary nerves; 13, ciliary ganglion and ciliary nerves; 14, pterygopalatine nerves; 15, pterygopalatine ganglion; 16, posterior superior nasal nerves; 17, pterygopalatine nerve; 18, posterior inferior nasal nerves; 19, greater superfi cial petrosal nerve; 20, lingual nerve; 21, submandibular ganglion; 22, pterygoid nerve; 23, facial nerve in the facial canal; 24, chorda tympani; 25, anterior auricular nerve; 26, otic ganglion Neoplasms of the Oral Cavity 107 pillar (part of the oropharynx), the mandible, and to the question of bone involvement (hard palate, man- the pterygomandibular space dorsally (and this way dible) CT is generally regarded to be slightly superior to the anterior parts of the parapharyngeal space and over MRI so that sometimes both methods add up to the skull base cranially), and to the palate medially. the fi nal diagnosis.