A pictorial review of the Benign and Malignant Conditions involving the Salivary Glands and Oral Cavity.

Transcription

1 A pictorial review of the Benign and Malignant Conditions involving the Salivary Glands and Oral Cavity. Poster No.: C-2266 Congress: ECR 2013 Type: Educational Exhibit Authors: L. Lavelle, J. F. Gerstenmaier, C. J. McCarthy, E. Ni Mhurchu, D. E. Malone, J. Griffin; Dublin/IE Keywords: Neoplasia, Infection, Congenital, Education, PET, MR, CT, Ear / Nose / Throat DOI: /ecr2013/C-2266 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 34

2 Learning objectives To review the anatomy of the salivary glands, oral cavity, adjacent structures, and possible routes for disease infiltration. To describe the spectrum of inflammatory, congenital, benign and malignant conditions involving the salivary glands and oral cavity. To illustrate the imaging features with examples of each condition with pathological correlation where appropriate. Self assessment quiz. Page 2 of 34

3 Background There are three major salivary glands, the parotid, submandibular and sublingual glands. Minor salivary glands are diffusely located throughout the aerodigestive tract. Infectious, inflammatory, congenital, benign and malignant conditions can involve the salivary glands. Detailed knowledge of the relevant anatomy is essential, and helps to provide a confident approach to image interpretation. We propose a guideline for the radiologist in evaluating various lesions based on characteristic imaging features and anatomical relationships. The parotid space contains the parotid gland which is located superficially and extends over the ascending ramus of the mandible. It is divided into two compartments; superficial and deep. The superficial lobe lies beneath the skin and extends superficial to the masseter muscle. The deep lobe extends deep to the plane of the facial nerve. Stensen's duct extends anteriorly over the masseter muscle and inserts in the cheek at the second maxillary molar. The parotid space contains parotid gland external carotid artery retromandilbular vein facial nerve intra parotid lymph nodes Page 3 of 34

4 Fig. 1: Axial T2 MRI demonstrating the parotid space containing the parotid gland. A;external carotid artery, V;retromandibular vein; FN;facial nerve. The floor of the mouth contains the submandibular, sublingual and minor salivary glands. The sublingual space is located superomedial to the myelohyoid musle and lateral to the genioglossus geniohyoid complex. The hyoglossus muscle (an extrinsic muscle of the tongue) extends from the hyoid bone through the sublingual space inserting into the lateral aspect of the tongue. This separates the lingual artery (lies medial to the hyoglossus muscle) from the lingual vein and whartons duct (submandibular duct) which lie lateral to it.the sublingual glands drain through multiple small ducts that open into the floor of the mouth. The anterior ducts may join to form a common Bartholin duct. Page 4 of 34

5 The sublingual space contains sublingual gland wharton's duct small portion of submandibular gland lingual artery and vein lingual nerve hyoglossus muscle Fig. 2: Axial T2 MRI demonstrating the sublingual space. GG; genioglossus geniohyoid complx, M;Myelohyoid muscle, H; hyoglossus muscle. Page 5 of 34

6 The submandibular space is inferior and lateral to the myelohyoid muscle and superior to the fascia lining the platysma muscle. The ramus of the mandible is lateral to the submandibular space. The submandibular space contains submandibular gland submental and submandibular nodal groups facial vein and artery hypoglossal nerve anterior belly of the digastric muscle Page 6 of 34

7 Fig. 3: Axial T2 MRI demonstrating the submandibular space. SG;submandibular gland, GG; genioglossus geniohyoid complex, H;hyoglossus, P;platysma, MA;masseter muscle, M;Myelohyoid muscle, N;submandibular lymph node, RM; ramus of mandible. There is no posterior fascial border between the sublingual and submandibular spaces allowing communication at the posterior myelohyoid margin. Similarly no fascial border separates these spaces from the inferior parapharyngeal space allowing for disease infiltration. Deep parotid space lesions may also infiltrate into the parapharyngeal space displacing the parapharyngeal fat anteriorly. Other important spaces include:the masticator space, carotid space, parapharyngeal space and the pharyngeal mucosal space. The masticator space contains temporalis muscle masseter muscle medial and lateral pterygoid muscles ramus and posterior body of mandible mandibular branch of trigeminal nerve The carotid space contains carotid artery internal jugular vein cranial nerves 9-12 The parapharyngeal space contains minor salivary glands fat internal maxillary artery ascending pharyngeal artery pterygoid venous plexus Page 7 of 34

8 Fig. 4: Axial T2 MRI. PPS; parapharyngeal space, PS; parotid space, MS;masticator space, CS;carotid space. The pharyngeal mucosal space extends to involve the nasopharynx, oropharynx and contains adenoids (nasopharynx) palatine and lingual tonsils (oropharynx) minor salivary glands pharyngobasilar fascia superior, middle and inferior constrictor muscles levator palatini muscle eustachian tube, torus tubarius Page 8 of 34

9 Fig. 5: Axial T1 MRI demonstrating the pharyngeal mucosal space. Page 9 of 34

10 Imaging findings OR Procedure details Benign conditions involving the salivary glands can be divided into: Sialolithiasis Non-Infectious Inflammation Infectious Inflammation Cystic Lesions Benign Tumours 1.Sialolithiasis Sialolithiasis is the second most common disease of the salivary glands after mumps. It typically presents with painful swelling of the gland. The submandibular gland is most commonly affected accounting for 85% of all salivary gland calculi due to the high mucus content of its secretions. Non contrast CT has the highest sensitivity for calculus detection. Page 10 of 34

11 Fig. 6: Axial and coronal non contrast CT demonstrating a calculus within the right parotid gland. Fig. 7: Axial and coronal contrast enhanced CT demonstrating a calculus within the left submandibular gland. A contrast enhanced CT was performed as the clinical question was unclear. Infectious Inflammation Paramyxo and cytomegalovirus are the most common viral infections of the salivary glands. Staph aureus is the most common bacterial infection. Granulomatous infections also occur- tuberculosis. If an abscess is suspected a contrast enhanced CT should be performed. Page 11 of 34

12 Fig. 8: Axial and coronal contrast enhanced CT demonstrating a diffuse mass containing air pockets within the submandibular space. Note the involvement of the right platysma muscle (blue arrow) and the normal left platysma muscle (yellow arrow). Non-Infectious Inflammation A number of autoimmune diseases involve the salivary glands including HIV, Sjogren disease and Sarcoidosis. Sjogren disease and sarcoidosis predispose to calculus formation. Sjogren disease also increases the risk of parotid lymphoma. Page 12 of 34

13 Fig. 9: Axial T1 and T2 fat sat sequences of the parotid gland. Note the salt and pepper appearance, low signal on T1 and high signal on T2 indicating tiny cystic spaces. Page 13 of 34

14 Fig. 10: Axial T1 and T1 post contrast sequences demonstrating some enhancement of the solid areas within the involved parotid gland. Page 14 of 34

15 Fig. 11: Axial T1 and T2 MRI sequences demonstrating bilateral intraparotid solid and cystic masses in a patient with known HIV. Page 15 of 34

16 Fig. 12: Axial T1 MRI pre and post contrast demonstrating enhancement post contrast. Cystic Lesions Cystic lesions involving the floor of the mouth are commonly seen. The most frequent is a ranula;which can be divided into simple and diving. A ranula is a mucous retention cyst with an epithelial lining which arises from the sublingual glands or minor salivary glands. A simple ranula lies within the sublingual space medial to the mylohyoid muscle. A diving ranula results from the rupture of a simple ranula which then extends posteriorly from the sublingual space into the submandibular space, and can also extend anteriorly through a myelohyoid defect into the submandibular space. The extension lacks an epithelial lining and is therefore classified as a pseudocyst. Page 16 of 34

17 Fig. 13: Axial and coronal T2 fat sat sequences demonstrating a diving ranula. Page 17 of 34

18 Fig. 14: Axial T2 fat sat sequences demonstrating a larger diving ranula. The second axial image show multiple septations within it. Other cystic masses which occur in the floor of the mouth include dermoid and epidermoid cysts. Retention cysts can also occur within the pharyngeal mucosal space. They are typically smooth well circumscribed round or oval lesions. Page 18 of 34

19 Fig. 15: Axial and coronal contrast enhanced CT demonstrating the nature of a pharyngeal mucosal retention cyst. Benign Solid Neoplasms The most common benign tumours of the major salivary glands are pleomorphic adenomas and Warthin tumours. Pleomorphic adenomas occur most frequently within the parotid gland and are slightly more common in women in the fourth and fifth decades of life. Low signal on T1 High signal on T2 Enhance heterogenously Usually solitary and unilateral May undergo malignant transformation (rarely) Page 19 of 34

20 Fig. 16: Axial T1 and T2 MRI sequences demonstrating a pleomorphic adenoma within the right parotid gland; low signal on T1, high on T2. Page 20 of 34

21 Fig. 17: Axial T1 fat sat MRI demonstrating heterogenous enhancement. Coronal T1 MRI. Pleomorphic adenomas may also occur within the deep lobe of the parotid gand, Iceburg tumour. Page 21 of 34

22 Fig. 18: Axial T1 and T2 MRI sequences demonstrating extension of a pleomorphic adenoma into the parapharyngeal space, known as an iceberg tumour. Warthin tumour makes up 5-10% of benign salivary neoplasms. They are more common in men in the fifth and sixth decades of life. T1 low signal T2 high signal, contains solid and cystic elements Increased uptake of technetium pertechnetate 10%-60% bilateral Smoking is a risk factor Occur in the tail of the superficial lobe Page 22 of 34

23 Fig. 19: Axial T1 and T2 MRI demonstrating a Warthin's Tumour within the left parotid gland. Page 23 of 34

24 Fig. 20: Coronal T1 MRI demonstrating involvement of the parotid tail. Intraparotid Lipoma Lipomas are easily identified on imaging, due to their characteristic features. On CT they are well defined low attenuation lesions, hyperechoic on ultrasound and T1 hyperintense on MRI. The floor of the mouth is the third most common site for lipomas. Page 24 of 34

25 Fig. 21: Contrast enhanced Ct demonstrating a lipoma within the right parotid space. Neoplastic Salivary Gland Disease The smaller the salivary gland, the higher the rate of malignancy; 20-25% parotid gland % submandibular gland 50-81% sublingual and minor salivary glands. The most common malignancy of the parotid gland is mucoepidermoid carcinoma. The most frequent malignancy of the submandibular gland is adenoid cystic carcinoma. It is usually slow growing and has propensity for perineural spread. Page 25 of 34

26 Fig. 22: Axial and coronal contrast enhanced CT. Note the the infiltrating nature of the lesion which extends to the carotid and parapharyngeal spaces. The coronal scan also demonstrates a metastatic lymph node. Mucoepidermoid carcinoma occurs mostly in patients aged between years. It varies in levels of differentiation, poorly differentiated being the most aggressive with increasing tendency to infiltrate. Fig. 22 on page Page 26 of 34

27 Fig. 23: Axial and coronal contrast enhanced CT demonstrating the lesion centered within the parotid space. However the coronal image demonstrates extension towards the foramen ovale within skull base. Squamous cell carcinoma, adenocarcinoma and acinic cell carcinoma of the salivary glands are less common. Enlarged lymph nodes commonly accompany these tumours. Page 27 of 34

28 Fig. 24: Axial and coronal contrast enhanced CT. The patient had previous surgery for squamous cell carcinoma involving the parotid gland, these images demonstrate recurrence within the parotid space. Note the involvement of the skin. Page 28 of 34

29 Fig. 25: Axial PET-CT images demonstrating FDG avid mass centered on the parotid gland, with an FDG avid metastatic lymph node evident on the right axial image. The parotid gland contains lymphatic tissue, the other salivary glands do not. This occurs as it encapsulates late in the second trimester. Lymphadenopathy may therefore also be seen within the parotid gland. Similarily lymphoma may occur in the parotid gland, either as primary lymphoma or an ifiltrative process. Page 29 of 34

30 Fig. 26: Axial T1 and T2 fat sat sequences demonstrating a well defined mass within the superficial lobe of the right parotid gland, biopsy revealed T cell lymphoma. Malignant tumours of the minor salivary glands may occur anywhere along the aerodigestive tract, the minor salivary glands being associated with a higher rate of malignancy. Page 30 of 34

31 Fig. 27: Axial and coronal T1 post contrast MRI demonstrating an infiltrating tumour involving the nasopharynx, masticator and parapharyngeal spaces. Note the involvement of the right medial pterygoid muscle on the axial image. Coronal image shows tumour extension through the right foramen ovale and meningeal involvement. The foramen ovale is normal on the left. Page 31 of 34

32 Conclusion Self Assessment Quiz 1.Simple ranulas occur in which space a)parotid space b)sublingual space c)parapharyngeal space d)submandibular space 2.Which gland has the highest rate of malignancy a)parotid gland b)submandibular gland c)minor salivary glands d)sublingual gland 3. Which malignant tumour has the highest propensity for perineural spread a)mucoepidermoid carcinoma b)adenocarcinoma c)squamous cell carcinoma d)adenoid cystic carcinoma 4. Which is the most common benign neoplasm of the parotid gland a)pleomorphic adenoma b)warthins tumour c)mucoepidermoid carcinoma d)adenocarcinoma Conclusion Following this review the Radiologist should be comfortable with the cross sectional anatomy of the salivary glands, oral cavity and skull base anatomy. Knowledge of the anatomy is essential to identify pathology and enables the Radiologist to provide a succinct differential diagnosis and to assess for tumour extension and metastases. Page 32 of 34

33 Fig. 28 Page 33 of 34

34 References 1.Bialek, E. J., Jakubowski, W., Zajkowski, P., Szopinski, K. T., & Osmolski, A. (2006). US of the Major Salivary Glands: Anatomy and Spatial Relationships, Pathologic Conditions, and Pitfalls. Radiographics, 26(3), doi: /rg La'Porte, S. J., Juttla, J. K., & Lingam, R. K. (2011). Imaging the Floor of the Mouth and the Sublingual Space. Radiographics, 31(5), doi: /rg Youssem, D.M., Kraut, M.A., Chalian, A.A.Major Salivary Gland Imaging. Radiology Neuroradiology: The Requisites, Youssem, Zimmerman, Grossman. 5.Kurabayashi T, Nakamura S, Ogura I, Sasaki T. The sublingual and submandibular spaces. Oral Radiol 2003;19(2): Harnsberger HR. Handbook of head and neck imaging. 2nd ed. St Louis, Mo: Mosby, Kurabayashi T, Ida M, Yasumoto M, et al. MRI of ranulas. Neuroradiology 2000;42(12): Page 34 of 34