Benign pathology of the salivary glands.

Transcription

1 Benign pathology of the salivary glands. Poster No.: C-2047 Congress: ECR 2015 Type: Educational Exhibit Authors: G. Price, S. R. Rice, S. Patel, S. Morley, T. Beale; London/UK Keywords: Ear / Nose / Throat, Head and neck, Ultrasound, CT, MR, Education, Education and training, Pathology DOI: /ecr2015/C-2047 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 30

2 Learning objectives The purpose of this educational exhibit is: To revise the anatomy of the major salivary glands; To understand the ultrasound approach to assessment of the major salivary glands; To recognise the imaging appearances of the most frequently encountered benign salivary pathology including sialolithiasis, sialadenitis and systemic illness such as Sjogrens disease. Background The major salivary glands can be affected by a wide range of pathology, however as these can be relatively uncommon the general radiologist may be unfamiliar with the imaging appearances. It is essential to be able to differentiate benign disease from malignancy. Ultrasound provides an easily accessible and non-invasive method of assessment of the major salivary glands. It is readily available and widely accepted as the first choice of imaging modality in Europe and Asia, whereas in the US the firstline is more often 1 MR or CT. As mainly superficial structures the salivary glands are ideally positioned to access with ultrasound, with the additional benefit of allowing for tissue diagnosis when necessary. Plain film can be useful to assess for radiopaque calculi in up to 80% of cases, and contrast sialography may demonstrate filling defects and ductal dilatation but is contraindicated in acute sialoadentitis. MR and CT are useful to provide further information regarding a mass, for example if it is large or within the deep lobe of the parotid where ultrasound views can sometimes be obscured. Findings and procedure details Anatomy of the major salivary glands Page 2 of 30

3 The paired parotid, submandibular and sublingual glands make up the major salivary glands. Further minor salivary glands are found over the palate, lips, cheeks, tonsils and tongue. 2 The parotid glands are the largest salivary glands and secrete only serous fluid. Each gland is positioned between the ramus of the mandible and the styloid process, with the 2 duct opening lateral to the second upper molar tooth. The internal jugular vein, external carotid artery and facial nerve traverse through the gland. The gland can be divided in to superficial and deep lobes by drawing a line from the posterior aspect of the mandibular ramus to the mastoid process. As the parotid develops it is encapsulated in the second trimester of pregnancy and incorporating lymphatic tissue, therefore lymph nodes can be seen within the parotid parenchyma. The other salivary glands do not contain lymph nodes, however lymphocytes are encountered. 3 Fig. 1: Anatomy of the parotid gland in axial section References: Ahuja, A. T., & Evans, R. M. (Eds.). (2000). Practical head and neck ultrasound. Cambridge University Press. Page 3 of 30

4 The submandibular glands are found along lingual surface of the body of the mandible, palpable inferolaterally to mylohyoid. The duct is around 5cm long and runs between the 2 mylohyoid and hyoglossus muscles. The sublingual glands are the smallest of the major salivary glands, found deep within 2 the sublingual space between the genioglossus muscle and mandible. Each gland has between 8-20 small ducts which open either side of the frenulum. Several of the ducts may also have a common drainage pathway with the submandibular duct. Fig. 2: Anatomy of the submandibular and sublingual glands References: Elsevier Ltd. Drake et al: Gray's Anatomy for Students. Ultrasound assessment of the major salivary glands The glands are best visualised with a high frequency transducer (10-15MHz) with assessment in two perpendicular planes. In addition, a curvilinear lower frequency (5-10MHz) can be used to assess the deep aspect of the parotid gland. The submandibular duct is best assessed firstly in a coronal plane with the probe perpendicular to the mandible. In this position the mylohyoid and hyoglossus muscles can be identified. The probe is then turned parallel to the mandibular body, providing an ideal position along the submandibular duct as it runs between the mylohyoid and hyoglossus muscles. Page 4 of 30

5 Tip: The lingual vein can be easily mistaken for the submandibular duct as it runs in the same plane. Ensure that any tubular structure does not have flow in it and cannot be followed past the gland. Fig. 3: Ultrasound probe position for visualisation of the submandibular duct. References: University College Hospital - London/UK Page 5 of 30

6 The use of a sialogogue can be particularly useful in assessment of the ducts (Fig. 4 on page 19). Care should be taken when scanning to apply very gentle pressure so not to obscure a dilated duct. The patient can also be asked to 'blow out the cheeks' to improve the view of the parotid duct opening and visualise a stone within the duct. Fig. 4: Parotid gland duct post and pre sialogogue References: University College Hospital - London/UK Benign Pathology of the Salivary Glands Sialolithiasis The clinical history is usually of recurrent pain and swelling of the affected gland, particularly before meals. 4 80% of salivary stones are found within the submandibular gland, of which 80-90% are radiopaque. The submandibular gland is more prone to stone formation because of the alkaline nature of the saliva which is thick and viscous, and also due to the dependent 3 position of the gland. 20% of calculi are found in the parotid gland, of which 50% are radiopaque. 4 Page 6 of 30

7 Fig. 5: Ultrasound of the submandibular duct demonstrating two ductal calculi with posterior acoustic shadowing References: University College Hospital - London/UK Tip: 25% of patients with stones will have multiple calculi, therefore it is important to 3 assess both sides ( Fig. 5 on page 20, Fig. 6 on page 20 ). Page 7 of 30

8 Fig. 6: Ultrasound of both submandibular glands demonstrating bilateral calculi (arrows) References: University College Hospital - London/UK Tip: Ductal dilatation can also be cause by a stricture or an obstructing mass lesion. Fig. 7: Plain occlusal radiographs demonstrating distal submandibular duct stones References: University College Hospital - London/UK Page 8 of 30

9 It is possible to demonstrate distal ductal calculi with plain film radiographs which may be difficult to visualise with ultrasound ( Fig. 7 on page 21 ). Sialadenitis Acute: Acute bacterial sialadenitis presents as a painful swelling commonly associated with purulent discharge. Most commonly caused by oral Streptococci, anerobes 4 and Staphylococcus aureus, potentially with areas of focal abscess formation. The symptoms are almost always unilateral. Viral infection primarily affects the parotid causing pain, fever and swelling, and most commonly due to mumps. Infection results in unilateral then bilateral swelling ( Fig. 8 on page 21 ). Page 9 of 30

10 Fig. 8: Ultrasound of the left submandibular gland demonstrating acute sialadenitis References: University College Hospital - London/UK Chronic / Recurrent: Chronic infection may be due to poor oral hygiene or secondary to chronic inflammation, for example as a result an obstructing stone or stricture. The salivary gland appears small and hypoechoic. This is also observed in the frail elderly population who are prone to dehydration. Recurrent disease results in ductal dilatation and ballooning of the alveoli called sialectasis. Page 10 of 30

11 Systemic disease - Sjögren's Disease Sjögren's is an autoimmune disease which affects the secretory glands, resulting in a dry mouth and dry eyes. It affects women nine times more often than men. On ultrasound the salivary glands may be enlarged, having hetergenous appearance with multiple small areas of hypoechogenicity, Fig. 9 on page 22. Labial gland biopsy is commonly used for diagnosis and demonstrates lymphocytic infiltrates. Tip: Patients with Sjögren's have 5% risk of lymphoma arising within the gland. Sjögren's produces a characeristic appearance on sialogram with multiple ductal system cavities, Fig. 10 on page 23. Fig. 10: MR sialogram - Sjogrens syndrome References: University College Hospital - London/UK Page 11 of 30

12 Systemic disease - HIV Severe immunodeficency presents in the salivary glands, commonly associated cervical lymphadenopathy. Patients present with diffuse salivary enlargement, mixed solid and/ or cystic lesions and both focal (parotid) and local (cervical) lymphadenopathy. On ultrasound the salivary glands are enlarged with a hetergenous appearance and multiple cysts. Multiple small areas of hypoechogenicity and small intra-glandal lymph nodes are also observed. Cystic lesions The majority of cystic lesions within the major salivary glands are benign. However, cystic lesions pose a diagnostic challenge where the walls of the lesion is irregular, nodular or the lesion contains a solid component. Frequently FNAC will be inaccurate if the wall is not appropriately sampled. Underlying malignancy needs to be carefully considered. Tip: Always be suspicious of the cystic lesion in a salivary gland - mucoepidermoid tumours are the most common type of salivary malignancy and can be predominantly cystic, Fig. 13 on page 26, Fig. 14 on page 27. Page 12 of 30

13 Fig. 13: Cystic lesion within the parotid gland (see also MRI), pathology proven mucoepidermoid tumour. References: University College Hospital - London/UK Page 13 of 30

14 Fig. 14: Cystic lesion of the left parotid gland (see also ultrasound image), pathology proven mucoepidermoid tumour. References: University College Hospital - London/UK Ranula A ranula is a mucocoele of the floor of the mouth arising from the sublinligual gland. A 'plunging' ranula represents a lesion that extends deep to mylohyoid and presents as both an intra-oral and extra-oral swelling. Benign parotid tumours Tip: Remember the rule of 80% for benign salivary lesions Page 14 of 30

15 80% of salivary gland masses are benign 80% are found within the parotid gland 80% lie within the superficial lobe 80% are pleomorphic adenomas Pleomorphic adenomas are usually lobulated, well defined masses with a clear outline and posterior acoustic enhancement. Page 15 of 30

16 Fig. 12: Ultrasound parotid - Pleomorphic adenoma References: University College Hospital - London/UK If the lesion is large or poorly visualised MR can help to delineate the lesion. Reassuring features on MR are - A low signal rim - Round/lobulated mass - High signal T2 Page 16 of 30

17 Of the remaining 20% of masses 10% are Warthins, and of these 10-20% are bilateral. Sialosis Non-inflammatory swelling of the major salivary glands, usually bilateral and most commonly affects the parotid. Associated with endocrine abnormalities, such as diabeties, chronic alcohol abuse but often idiopathic. Images for this section: Fig. 1: Anatomy of the parotid gland in axial section Page 17 of 30

18 Fig. 2: Anatomy of the submandibular and sublingual glands Page 18 of 30

19 Fig. 3: Ultrasound probe position for visualisation of the submandibular duct. Page 19 of 30

20 Fig. 4: Parotid gland duct post and pre sialogogue Fig. 5: Ultrasound of the submandibular duct demonstrating two ductal calculi with posterior acoustic shadowing Page 20 of 30

21 Fig. 6: Ultrasound of both submandibular glands demonstrating bilateral calculi (arrows) Fig. 7: Plain occlusal radiographs demonstrating distal submandibular duct stones Page 21 of 30

22 Fig. 8: Ultrasound of the left submandibular gland demonstrating acute sialadenitis Page 22 of 30

23 Fig. 9: Ultrasound parotid - Sjogren's syndrome Page 23 of 30

24 Fig. 10: MR sialogram - Sjogrens syndrome Page 24 of 30

25 Fig. 11: Ultrasound of the submandibular gland in a patient with HIV - note the large cysts and heterogeneity. Page 25 of 30

26 Fig. 12: Ultrasound parotid - Pleomorphic adenoma Page 26 of 30

27 Fig. 13: Cystic lesion within the parotid gland (see also MRI), pathology proven mucoepidermoid tumour. Page 27 of 30

28 Fig. 14: Cystic lesion of the left parotid gland (see also ultrasound image), pathology proven mucoepidermoid tumour. Page 28 of 30

29 Conclusion A number of benign conditions can present in the paired major salivary glands. Ultrasound provides a non-ionising, relatively inexpensive and reproducible method of assessment in superficial lesions, whereas cross-sectional imaging such as MRI is reserved for larger or more complex lesions. We present the imaging characteristics of the most frequently encountered benign salivary pathology. Personal information Dr Scott Rice: UCL Centre for Medical Imaging, 3rd Floor East, 250 Euston Road, London NW1 2PG. scott.rice@ucl.ac.uk Dr Gemma Price: UCLH Foundation NHS Trust, 235 Euston Road, London NW1 2BU. Dr Shivani Patel: UCLH Foundation NHS Trust, 235 Euston Road, London NW1 2BU. Dr Simon Morley: UCLH Foundation NHS Trust, 235 Euston Road, London NW1 2BU. Dr Timothy Beale: UCLH Foundation NHS Trust, 235 Euston Road, London NW1 2BU References Page 29 of 30

30 1. Bialek EJ, Jakubowski WJ, Zajkowsi P, Szopinski KT, Osmolski A. US of the major salivary glands: Anatomy and spatial relationships, pathologic conditions and pitfalls. Radiographics 2006; 26: Moore KL, Dalley AF. Clinically orientated anatomy, Fourth edition. Lippincott, Williams and Wilkins. 3. Yousem DM, Kraut MA, Chalian AA. Major Salivary Gland Imaging. Radiology 2000; 216: Weissleder, R. (2011). Primer of diagnostic imaging. Page 30 of 30