Salivary gland tumorsare variable in location, origin, and malignant potential. Epub 2017 Jun 13. Space occupying lesions of parotid gland. Cho CM, Tong SL, Bhatia KS, Wong KT, Yuen HY, Lee YP, Ahuja AT. Will I need reconstructive surgery? Parotid tumor treatment often involves surgery to remove the tumor. Comparative diagnostic imaging and pathological analysis of echo color/power Doppler and of magnetic resonance imaging. Adenoid cystic carcinoma. Patients may have blood tests or imaging tests as part of regular follow-up care. Sonohistology for the computerized differentiation of parotid gland tumors. The site is secure. Facial nerve involvement generally suggests a malignant tumor, which may present with pain or paralysis. Lyu HX, Wang ZR, Gao YQ, Yu M, Li BQ, Zhang ZB. Hugh CD. Chemotherapy uses strong medicines to kill cancer cells. In: Carlson ER, Ord R (eds) Textbook and color atlas of salivary gland pathology. Salivary fistula: saliva leaking through the incision (this is usually temporary), Sialocele: a cavity or cyst containing saliva, Freys syndrome: a rare complication of parotid gland surgery that causes sweating or flushing in an area of the face when eating, especially spicy, salty or sour foods, Seroma: a pocket of serum that forms near the surgical incision. Masses of the parotid gland can represent both benign and . 2005 Oct;31(10):1287-96. doi: 10.1016/j.ultrasmedbio.2005.06.011. Salivary glands are a common source of benign pathology; malignant tumors are rare. sympathetic: via plexus surrounding external carotid artery from the superior cervical ganglion, parasympathetic: otic ganglion via the auriculotemporal nerve, sensory:auriculotemporal nerve, greater auricular nerve, facial process: anterior extension of glandular tissue along the parotid duct continuous with the main gland, congenital agenesis: either unilateral and bilateral 10. L'intensit di segnale nelle immagini T1-pesate e T2- pesate e l'impregnazione post-contrastografica si sono rivelate utili nella diagnosi differenziale tra adenoma pleomorfo e tumore di Warthin. ), which permits others to distribute the work, provided that the article is not altered or used commercially. How long will it take to heal? official website and that any information you provide is encrypted 2021 Jul 7;11:669542. doi: 10.3389/fonc.2021.669542. Bookshelf There is thus an increasing recognition that operations less than the traditional procedures are acceptable. 2016: 2672496. JSciMed Central publishes international, peer-reviewed science, medicine, and engineering journals. Would you like email updates of new search results? Masks are required inside all of our care facilities. This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) Benign lesions tend to be more common in women, but malignant lesions tend to occur with equal frequency in both genders. and transmitted securely. 2000;216(1):19-29. Five-year survival averages about 70%. 10. 2001;21 (5): 1211-27. J Laryngol Otol. Preoperative identification of benign versus malignant parotid masses: a comparative study including positron emission tomography. The differential diagnosis of a parotid lesion is broad, and the otolaryngologist must consider inflammatory, neoplastic, autoimmune, traumatic, infectious, or congenital causes. A prophylactic selective neck dissection (levels I to III) should be performed for patients with high-stage (T3/T4) disease-free clinically high-grade tumors (i.e., high-grade mucoepidermoid carcinoma, carcinoma ex-pleomorphic adenoma, adenocarcinoma, squamous and undifferentiated carcinomas). It is important to seek out an experienced head and neck surgeon to perform this procedure. National trends in inpatient parotidectomy: A fourteen-year retrospective analysis. 9. Howlett DC, Kesse KW, Hughes DV, Sallomi DF. Will I have a scar? Mansour N, Stock KF, Chaker A, Bas M, Knopf A. Ultraschall Med. It is important to recognize that the clinical behavior of a tumor rather than the histology can provide a better treatment guide, and it is recommended that clinical factors, in addition to histology and grade, are considered when treatment planning. The survival rates of patients with salivary gland cancer depend on the histological type and the stage of cancer. Mutations of P53, MDM2, Bcl-2, and ras have been found in both benign and malignant lesions. Ultrasound scan (USS) provides invaluable information about the site, size, and nature of salivary gland tumors and the presence of any significant cervical lymphadenopathy. ed that the ratio of malignancy in salivary gland tumors in children was . Superficial parotidectomy with identification and exposure of was traditionally the preferred procedure. J Otolaryngol Head Neck Surg. Operations used to remove parotid tumors include: To get to the parotid gland, surgeons make a cut in the skin near the ear. The differential for cystic parotid lesions includes: bilateral cystic parotid lesions Warthin tumor benign lymphoepithelial lesions of HIV Sjgren syndrome sialoceles dysgenetic polycystic disease of salivary glands unilateral cystic parotid lesion (s) Warthin tumor sialocele first branchial cleft cyst parotid cystic lymphangioma eCollection 2022 Feb. Vernuccio F, Arnone F, Cannella R, Verro B, Comelli A, Agnello F, Stefano A, Gargano R, Rodolico V, Salvaggio G, Lagalla R, Midiri M, Lo Casto A. Br J Radiol. Cystic lesions observed in parotid glands are relatively rare and comprise 2-5% of all parotid primaries. This site complies with the HONcode standard for trustworthy health information: verify here. A painless swelling on one side of your face may indicate a mass or tumor on your parotid gland. The facial nerve may be encased in scar tissue, so the traditional method of finding it may have to be augmented by exposing it in the mastoid bone, or more hazardously a peripheral branch traced back. [4]Patients with malignant lesions typically present in theirsixth decade. 2015 May-Jun;81(3):301-6. doi: 10.1016/j.bjorl.2015.03.007. [1]Salivary gland tumors are characterized by diverse histological appearances and variable biological behavior. 13. Salivary gland neoplasms may be benign or malignant, and malignant tumors can be primary or metastatic. parotid gland : 70% minor salivary glands (including sublingual): 22% with the palate being most frequent (see: minor salivary gland tumors) submandibular gland : 8% Overall ~80% of all parotid masses are benign and the majority of these are pleomorphic adenomas. Results: There were 96 benign and 28 malignant lesions in our cohort. Diagnostic performance of qualitative and radiomics approach to parotid gland tumors: which is the added benefit of texture analysis? This article reviews the key history and physical elements and adjunctive diagnostic tools available for working up parotid lesions. It is rare in the parotid. Salivary gland tumors are characterized by diverse histological appearances and variable biological behavior. 2016 Oct;37(5):454-471. doi: 10.1055/s-0042-109171. Biopsy; Malignancy; Mass; Parotid; Radiology. Most parotid gland tumors (80%) are benign and . 2013; doi:10.1001/jamaoto.2013.5217. These procedures should be undertaken by expert surgeons in carefully selected cases, e.g., small tumors confined to the superficial lobe. We are vaccinating all eligible patients. At Another Johns Hopkins Member Hospital: Masks are required inside all of our care facilities, COVID-19 testing locations on Maryland.gov, nerve transfer or other facial reanimation procedure, Learn more about the Salivary Gland Center. 2017 Aug;274 (8):3231-3240. doi: 10.1007/s00405-017-4636-2. 1993;86 (3): 268-80. Typical findings of Warthin's tumour included hyperintense components on T1w images (p < 0.001), location in the parotid inferior process (p < 0.001) and mild or incomplete contrast enhancement (p = 0.01). Primer of Diagnostic Imaging with CD-ROM. 1: digastric muscle 2: main trunk of the facial nerve 3: cervical branch of the facial nerve 4: marginal mandibular branch of the facial nerve 5: great auricular nerve divided distally. Keywords: The external carotid artery forms its two terminal branches within the parotid gland: maxillary and superficial temporal artery 13. Approximately 300 cases per year of primary salivary gland malignancy are registered in the United Kingdom, of which fewer than ten occur in children. http://creativecommons.org/licenses/by-nc-nd/4.0/. 2021 Dec;94(1128):20210340. doi: 10.1259/bjr.20210340. 2018 Apr;275(4):987-995. doi: 10.1007/s00405-018-4895-6. [2]It is not surprising that with such a wealth of pathology, clinical features, investigation issues, and contentious treatment options that salivary gland neoplasms are regularly used in clinical examinations. Acta Otorhinolaryngol Ital. All patients with a mass in a salivary gland should have an inspection and palpation of the mass itself. Warthin tumor is the 2nd most common benign lesion. eCollection 2021. Bilateral parotid tumors are most common in Warthin tumors and HIV related lymphoepithelial cysts. Questo studio retrospettivo si basa sulla valutazione di esami RM pre-chirurgici di 94 pazienti con tumori parotidei. Rapid growth, pain, tethering of the skin, ulceration of the skin, cervical lymphadenopathy, and facial nerve paralysis are all suggestive of malignancy. Loss of appetite. Advanced magnetic resonance imaging findings in salivary gland tumors. The patient concluded adjuvant radiotherapy and continued follow-up surveillance without evidence of relapse. sharing sensitive information, make sure youre on a federal Front Oncol. There is a high rate of transient facial nerve paresis in this group of patients. You should avoid heavy lifting and straining, and follow your doctors instructions, including keeping the wound clean and dry. The accessory parotid gland and facial process of the parotid gland on computed tomography. Sakamoto M, Sasano T, Higano S, Takahashi S, Iikubo M, Kakehata S. Dentomaxillofac Radiol. 4. The glands will be enlarged and heterogeneous with increased vascularity as shown below. There is fatty infiltration or fatty replacement of the parotid glands with age 6. superior pole:external acoustic meatus,temporomandibular joint, lower pole: behind the angle of the mandible, anterior to the sternocleidomastoidand posterior belly of the digastric, anterior surface: clasps the ramus of the mandiblewith the masseteron its outer surface and medial pterygoidon its inner surface inferiorly (separated by the stylomandibular ligament), anterior border: formed by the lateral edge of the anterior surface where it meets the masseter, the parotid ductand five facial nervebranches emerge from this border, from the deeper part, the superficial temporaland maxillary arteriesleave the gland, deep surface: indented by the mastoid process and its attached muscles (sternocleidomastoidand posterior belly of the digastric),styloid processand its attached muscles (stylohyoid,styloglossus,stylopharyngeus) and two ligaments (stylomandibular,stylohyoid), the external carotid arteryenters the gland through this surface, the styloid processseparates the gland from the internal jugular veinand internal carotid artery, the temporozygomatic and cervicofacial branches of the facial nerve enter the gland between the mastoidand styloid processes8, ADVERTISEMENT: Supporters see fewer/no ads, arterial: external carotid artery and a specific branch of the artery, the transverse facial artery, venous drainage:the retromandibular vein drains the parotid gland and eventually into the external jugular vein. These lesions are firm and are identified using electron microscopy. "Mayo," "Mayo Clinic," "MayoClinic.org," "Mayo Clinic Healthy Living," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research. You are not required to obtain permission to distribute this article, provided that you credit the author and journal. doi: 10.1016/j.ejrad.2008.01.027. Recurrence will occur if there has been incomplete excision and may occur if there has been tumor spillage. The histopathological diagnosis was confirmed after parotidectomy for each lesion. It is a relatively painless procedure, has few complications (seeding of the tumor does not seemto occur), and may prevent an ill-advised and often ill-fated incisional or excisional biopsy of a parotid mass. Epidemiology. These slow-growing lesions are benign and likely to occur in the minor salivary glands. J R Coll Surg Edinb. If your doctor suspects a tumor in this area, he or she is likely to recommend several steps to diagnose and evaluate it. Imaizumi A, Kuribayashi A, Okochi K, Ishii J, Sumi Y, Yoshino N, Kurabayashi T. Differentiation between superficial and deep lobe parotid tumors by magnetic resonance imaging: usefulness of the parotid duct criterion. stata effettuata un'analisi statistica per identificare le caratteristiche RM pi indicative di malignit e per definire l'aspetto tipico degli istotipi pi comuni. Histology results were available for all tumours. A "lumpectomy" is not considered an appropriate procedure due to high recurrence rates. The universal treatment for salivary gland tumors is surgery; hence, patients need to be told about the potential complication, including recurrence. In general, the ratio of benign to malignant tumors is proportional to the gland size; i.e. They can be confused with Warthin tumor on cytology, and larger tissue samples are usually requested, and immunohistochemistry is required. Results of the examinations were compared with those ones of histology. World Journal of Otorhinolaryngology Head and Neck Surgery. It is an Open Access platform to support scientific innovation and advancement in the research community by increasing access to peer-reviewed quality research articles. Epub 2022 Feb 9. 2022 May 1;51(4):20210484. doi: 10.1259/dmfr.20210484. Federal government websites often end in .gov or .mil. This content does not have an English version. The distinction between tumor types can be difficult, particularly based on material from fine-needle aspiration (FNA). Mortality from salivary gland tumors depends on the stage. The parotid gland is wrapped around the mandibular ramus and extends to a position anterior and inferior to the ear. Eisele says that tumor surgery on one parotid gland is not likely to affect a persons saliva level since there are so many other salivary glands that can compensate. Front Oncol. HHS Vulnerability Disclosure, Help The following MRI parameters were evaluated: shape, site, size, margins, signal intensity (SI) on T1w and T2w images, contrast enhancement, signal of cystic content, presence or absence of a capsule, perineural spread, extraglandular growth pattern and cervical adenopathy. The overall 5-year survival rate for salivary gland cancer is 72%. When a patient arrives at the CENTER experiencing swelling of the parotid gland Dr. Larian will perform a physical examination, imaging tests and a fine needle biopsy to determine whether the mass is cancerous. (, Warthin's tumour of the left parotid gland. Unusual presentation of parotid gland adenoid cystic carcinoma : A case presentation and literature review. 2008;66:419436. Results from a needle biopsy aren't always correct. Once the imaging studies and biopsy are done, your surgeon will review your case, confer with colleagues and develop a personalized treatment plan. The tumor is more common in men than women and is known to be bilateral in 10%-15% of cases. This nerve is called the facial nerve. Cross-sectional imaging and cytologic investigations in the preoperative diagnosis of parotid gland tumors - An updated literature review. Tumors were divided into 5 histological subtypes, and different MRI features were compared between groups. A functioning facial nerve should be preserved unless found to be infiltrated with the tumoritself at the time of resection. Multiparametric magnetic resonance imaging of parotid tumors: A systematic review. The major salivary glands are the submandibular (below the jaw), the sublingual (under the tongue) and the parotid glands, which are located by the angle of your jaw in front of the ear. Partial parotidectomy or hemi-superficial parotidectomy has become commonplace. Keywords: Salivary gland tumors are uncommon in children, but a greater proportion of them (30%) are malignant and are usually low-grade mucoepidermoid carcinoma. The predictive values were: PPV 50% and NPV 68.8%, respectively. There are many salivary glands in the lips, cheeks, mouth and throat. official website and that any information you provide is encrypted Exposure to nitrosamines and mortality from salivary gland cancer among rubber workers. Since "parotid masses" are frequently of nonparotid origin (Table 175.1), the relationship of the mass to the gland markedly alters the management in as many as a third of patients presenting with a parotid-region mass (Figs. Assessment of Risk of Xerostomia After Whole-Brain Radiation Therapy and Association With Parotid Dose. 2017 Oct;104(10):850-857. doi: 10.1016/j.bulcan.2017.09.001. Eur J Radiol. contribution of apparent diffusion coefficient histogram analysis findings in differential diagnosis of parotid gland masses. During the follow-up care,the otolaryngologist can give patients personalized information aboutthe risk of recurrence. Lowe LH, Stokes LS, Johnson JE et-al. Facial nerve assessment is mandatory, as is neck node palpation. The Role of Radiomics in Salivary Gland Imaging: A Systematic Review and Radiomics Quality Assessment. Evaluation of parotid gland lesions with standard ultrasound, color duplex sonography, sonoelastography, and acoustic radiation force impulse imaging - a pilot study. Earring lesions of the parotid tail. On the other hand, lesions occurring in the submandibular gland and the minor salivary glands are more likely to be malignant. Parotid tumors can involve the superficial lobe or deep lobe of the parotid gland. doi: 10.1016/j.suronc.2003.10.002. They are of 2 types: Benign or non-cancerous Malignant or cancerous In certain cases, the growth inside the parotid gland may not originate from parotid tissues but originate from enlarged lymph nodes which invade the glands. Elsevier Australia. Our aim was to define typical magnetic resonance (MRI) findings in malignant and benign parotid tumours. Salivary gland disorders. The role of imaging in the evaluation of parotid disease. 6. Methods: A total of 124 patients with parotid gland lesions for whom surgery was planned were examined using conventional ultrasound, Doppler examination, and shear wave elastography. The cut is often hidden in a crease of skin or behind the ear. Preoperative tumor localization, differential diagnosis, and subsequentselection of appropriate treatment for parotid gland tumors is critical.However, the relative rarity of these tumors and the highly dispersed tissuetypes have left an unmet need for a subtle differential diagnosis of suchneoplastic lesions . The approach is based on the characteristics of the tumor whether it is benign or malignant. Would you like email updates of new search results? When this happens, you might experience weakness of your face, or a part of it, on one side. The parotid glands are two salivary glands that sit just in front of the ears. Epub 2018 Feb 12. Recovery typically takes one to two weeks after the operation. Talati V, et al. Mayo Clinic does not endorse companies or products. Following surgery, the patient developed temporary facial paralysis. The .gov means its official. Chills. 8600 Rockville Pike Histology results were available for all tumours. Berlin Heidelberg: Springer-Verlag; 2007. pp. If surgery isn't possible, radiation therapy might be the first treatment for parotid cancers. 2021 Apr 28;11:644150. doi: 10.3389/fonc.2021.644150. Malignant parotid gland neoplasms; Monomorphic adenoma; Parotid gland tumor; Pleomorphic adenoma; Ultrasound. Martino M, Fodor D, Fresilli D, Guiban O, Rubini A, Cassoni A, Ralli M, De Vincentiis C, Arduini F, Celletti I, Pacini P, Polti G, Polito E, Greco A, Valentini V, Sorrenti S, D'Andrea V, Masciocchi C, Barile A, Cantisani V. Gland Surg. This could be with radiation therapy and chemotherapy. Sialography is a sensitive and reliable method and has been used as a gold standard in the diagnosis of SS. In these situations, chemotherapy might be done at the same time as radiation therapy. Bethesda, MD 20894, Web Policies Olsen KD, et al. Parotid swelling or enlargement can be unilateral or bilateral, suggesting different underlying causes. There are many other salivary glands in the lips, cheeks, mouth and throat. 7th ed. The staging of metastatic neck nodes for salivary gland cancer is similar to that for other metastatic diseases. Moore EJ (expert opinion). Epub 2016 Feb 20. Epub 2016 Jun 14. A CT scan is the best investigation to distinguish between these two differential diagnoses. Acinic cell carcinoma (ACC) is a rare malignant tumor, arising almost exclusively in the salivary glands in which it accounts for 11% of malignant neoplasms. In the lab, tests can show what types of cells are involved and tell if they're cancerous. Headache. 2. Cigarette smoking and alcohol is associated with head and neck squamous cell carcinoma, skin malignancies in the head and neck have been known to metastases to the parotid glands. I parametri significativamente predittivi di malignit sono risultati i margini mal-definiti (p < 0,001), le linfoadenopatie (p < 0,001) ed il pattern di crescita infiltrativo (p < 0,001). Lymphomas may develop in intra-parotid lymph nodes. Parotid tumors usually do not cause pain, Eisele notes. Parotitis is inflammation of the parotid gland. Anticancer Res. Dentomaxillofac Radiol. The parotid glands are the most common place that salivary gland tumors happen. ( a ) Coronal T2w image,, Atypical pleomorphic adenoma of the right parotid gland. Tumors low in the tail of the parotid gland can easily be confused with an upper cervical lymph node. the differential diagnosis of diseases that occur with increased volume in the head, lymphadenopathy, drooling, dysphagia, and progressive weight loss. Examples of criteria for the description of the echogenicity (slightly hypoechoic, highly hypoechoic), US of malignant parotid glands tumors: SCCpoor defined margins, highly hypoechogenic, slightly heterogenic,, US of: PA with irregular shape, well-defined margins, slightly hypoechogenic, slightly heterogenic, and, US of different pleomorphic adenomas: a1 , a2 polycyclic shape, highly hypoechogenic, highly, Receiver operating characteristic curves for, Receiver operating characteristic curves for malignant and benign parotid tumors, Receiver operating characteristic curves for pleomorphic adenomas/adenolymphomas of parotid gland, MeSH (2006) ISBN: 0323040683. official website and that any information you provide is encrypted A single copy of these materials may be reprinted for noncommercial personal use only. Differential diagnosis; Histology; Magnetic Resonance Imaging; Neoplasms; Parotid gland. For this reason, some doctors don't do a biopsy before surgery. There is one on each side of the face. calculus Bilateral mumps sarcoidosis lymphoma Mikulicz syndrome (early Sjogrens, bilateral, painless) alcohol-associated parotitis An association has been reported between mucoepidermoid carcinoma and myasthenia. MeSH Please enable it to take advantage of the complete set of features! 2009;75:497501. ?Brien C. Primary and Metastatic Cancer of the Parotid: Comparison of Clinical Behavior in 232 Cases. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. They might use electrical devices to check on the nerve and make sure it works as expected after surgery. All patients underwent DCE-MRI examination for pre-surgery evaluation of parotid gland tumors. It is important to note that both alcohol and smoking are not linked to salivary gland tumors, except for Warthin tumors. Cantisani V, David E, Sidhu PS, Sacconi B, Greco A, Pandolfi F, Tombolini M, Lo Mele L, Calliada F, Brunese L, Catalano C, De Vincentiis M, Di Leo N, Ascenti G, D'Ambrosio F. Ultraschall Med. How will you be sure that you've removed all of the tumor? Ultrasound-guided fine needle biopsy can be done if neck mass is not easily palpable. Yu Q, Wang A, Gu J, Li Q, Ning Y, Peng J, Lv F, Zhang X. Salivary Duct Carcinoma of the Parotid Gland. Izzo L, Casullo A, Caputo M et-al. Typical findings of pleomorphic adenoma included hyperintensity on T2w images (p = 0.02), strong contrast enhancement (p < 0.001) and lobulated shape (p = 0.04). Keywords: Warthin tumor; Parotid gland; Diagnosis . The infected parotid or submandibular gland will present as a warm, tender, enlarged gland. The majority of patients first present to the primary care clinician or nurse practitioner with complaints of a painless lump. If the patient is suspected of having metastatic spread, the use of F-18 fluorodeoxyglucose PET scan is useful. -, Carlson ER, Ord R (2008) Tumors of the Parotid Gland. Informed consent was obtained from all individual participants included in the study. This is a reliable way to help your head and neck surgeon determine characteristics of the tumor. The pathologist tells the surgeon if the tumor is cancerous. MRIof the head and neck is the preferred method, but in some cases aCT scanor other imaging studies are used. A few weeks delays can make a significant difference to the complexity of the planned surgery, with tumors readily invading the skin andsurrounding structures. Parotid gland lesions in children can be divided into benign or malignant. Adjuvant postoperative radiation therapy (RT) can be given in such cases, but this should be discussed in an interprofessional team setting. Does routine preoperative imaging of parotid tumours affect surgical management decision making?. Unable to load your collection due to an error, Unable to load your delegates due to an error. Comparative Study of Qualitative and Quantitative Analyses of Contrast-Enhanced Ultrasound and the Diagnostic Value of B-Mode and Color Doppler for Common Benign Tumors in the Parotid Gland. Sometimes the results say a tumor isn't cancerous when it is. 5. Patients with lung metastases may live up to 5 years before succumbing to the disease. 8600 Rockville Pike Before Parotid gland tumors: a retrospective study of 154 patients. The https:// ensures that you are connecting to the 2022; doi:10.1002/wjo.2.50. World J Radiol. ( The radiation can kill any cancer cells that remain. Local recurrences are common, and distant metastases occur in 30% to 40% patients, usually in the lungs, many years later. The patients often complain of facial pain and may present with facial paresis. The most common type of biopsy used for parotid masses is afine needle aspiration biopsy. This study is based on retrospective evaluation of pre-surgical MRI of 94 patients with parotid gland tumours. The most common type, pleomorphic adenoma, is slow-growing and has a low chance of becoming malignant. Parotid Gland Lesions: Multiparametric Ultrasound and MRI Features. Acta Otorhinolaryngol Ital. Parotid gland tumors account for approximately 2% to 10% of head and necktumors. (2012) ISBN: 9783642178689. Theme: Parotid gland disease A. Pleomorphic adenoma B. Adenoid cystic carcinoma C. Sarcoid D. Sjogrens syndrome E. Sialolithiasis F. Wharthins tumour Please select the most likely explanation for the following patients with parotid gland Cheung RL, Russell AC, Freeman J.