© 2006 WebMD, Inc. All rights reserved.                                                     ACS Surgery: Principles and Pr...
© 2006 WebMD, Inc. All rights reserved.                                                    ACS Surgery: Principles and Pra...
© 2006 WebMD, Inc. All rights reserved.                                                      ACS Surgery: Principles and P...
© 2006 WebMD, Inc. All rights reserved.                                                         ACS Surgery: Principles an...
© 2006 WebMD, Inc. All rights reserved.                                                           ACS Surgery: Principles ...
© 2006 WebMD, Inc. All rights reserved.                                                          ACS Surgery: Principles a...
© 2006 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and ...
© 2006 WebMD, Inc. All rights reserved.                                                                           ACS Surg...
© 2006 WebMD, Inc. All rights reserved.                                                                                  A...
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Acs0202 Parotid Mass

  1. 1. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 1 2 PAROTID MASS Ashok R. Shaha, M.D., F.A.C.S. Approach to Evaluation of a Parotid Mass There are three major salivary glands in the human body—the Nonneoplastic The causes of nonneoplastic masses include parotid gland, the submandibular gland, and the sublingual congenital, granulomatous, infectious or inflammatory, and non- gland—of which the parotid gland is the largest. In addition, there inflammatory conditions. Some congenital lesions (e.g., heman- are approximately 600 to 800 minor salivary glands distributed gioma or vascular malformation) present as a vague swelling in the throughout the entire upper aerodigestive tract, starting from the parotid region that has been present since childhood. One con- lip and extending to the lower end of the esophagus and up to the genital lesion, a first branchial cleft cyst, presents as a mass inferi- pulmonary alveoli. Almost half of these minor salivary glands are or to the cartilaginous ear canal, with a cyst tract that can be either on the hard palate. Accordingly, any mass on the hard palate medial or lateral to the facial nerve and may even divide the trunk should be considered a minor salivary gland tumor until proved of the nerve. This cyst is most commonly noted in the second otherwise.1 through fourth decades in life. The majority of salivary gland tumors originate in the parotid Granulomatous diseases are frequently manifested by an gland. Approximately 75% to 80% of parotid tumors are asymptomatic, gradual enlargement of a lymph node within the benign.2,3 In the evaluation and surgical treatment of parotid gland; often, they cannot be readily distinguished from neoplasms. tumors, it is essential to maintain awareness of the possibility of In sarcoidosis, salivary gland involvement may cause duct obstruc- temporary or permanent facial nerve injury [see Discussion, Prin- tion, pain associated with the duct, xerostomia, or enlargement of ciples of Facial Reanimation, below]. Because surgery necessarily the gland. The diagnosis is supported by chest x-rays that show entails some risk of an injury to this structure or its branches, as bilateral hilar adenopathy and by elevated levels of angiotensin- well as because most parotid masses do not give rise to significant converting enzyme (ACE). symptoms, many patients with parotid tumors may find the As noted (see above), infectious or inflammatory diseases prospect of surgical therapy difficult to accept. involving the parotid, unlike neoplasms, tend to give rise to pain in their early stages. Most such inflammatory conditions begin with diffuse enlargement of one or more salivary glands. Although Clinical Evaluation parotitis is generally unilateral, it may be bilateral if a systemic causative condition is involved, and other salivary glands may be HISTORY affected as well.The pain reported may be related to the presence Evaluation of a parotid mass begins of a stone in the salivary duct or to diffuse obstructive parotitis. with a good clinical history. The most Chronic parotitis may lead to recurrent infection and inflamma- important question is, how long has the tion.When recurrent swelling of the salivary gland does occur, it is mass been present? If local pain and directly related to eating and increased salivation. swelling of recent onset (i.e., within the Sialadenosis is a noninflammatory, nonneoplastic condition of past few days) are reported, infection or unknown origin that is characterized by diffuse enlargement of the obstruction is the likely cause. If the mass has been present for a salivary gland, with no discrete mass or inflammation. longer period (i.e., weeks to months), a neoplasm is more likely. Unfortunately, the presentations of some nonneoplastic condi- Lymphoepithelial Lymphoepithelial lesions may be divided tions resemble those of neoplasms, and distinguishing one type of into lymphocytic infiltrative diseases and lymphomas. In many condition from the other can be challenging. Thus, the history cases, patients with lymphocytic infiltrative diseases (e.g., Mikulicz should continue with further questions focusing on local or sys- disease, sicca complex, and Sjögren syndrome) have had their temic signs and symptoms, the presence of swelling or other mass- conditions for long periods, and they may feel that they have es in the salivary glands, and previous medical conditions (includ- always been chubby, when in fact they have had chronic enlarge- ing skin cancer). ment of both parotid glands. In patients with Sjögren syndrome, Classification malignant transformation to high-grade lymphoma is known to occur. Lymphoepithelial cysts are benign cystic lesions that may Major salivary gland masses can be classified as nonneoplastic, arise from lymph nodes or from lymphoid aggregates in the sali- lymphoepithelial, or neoplastic.4 vary gland. These lesions may be associated with HIV infection.
  2. 2. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 2 Approach to Evaluation of a Parotid Mass Patient presents with parotid mass Obtain clinical history. Perform physical examination of parotid region, focusing on extent of parotid disease, localized effects of lesion, and any motor or sensory deficits. Diffuse enlargement is present Solitary mass is identified Diagnosis is obvious Diagnosis is uncertain Plan treatment (conservative Initiate further workup: or surgical, as indicated). • Imaging (CT, MRI, ultrasonography, sialography, ?sialoendoscopy, ?PET) • FNA biopsy (routine use is controversial) Lesion is benign Lesion is malignant Treat surgically with superficial Treat surgically with superficial, total, or parotidectomy, preserving radical parotidectomy, as necessary, facial nerve. preserving facial nerve if possible. If cervical lymphadenopathy is present, consider elective neck dissection (comprehensive or selective, as appropriate). Provide postoperative radiotherapy for all patients except those with T1 or T2 tumors of low-grade histology and clear margins.
  3. 3. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 3 Primary lymphoma of the salivary gland is uncommon, occur- The most common presentation of a parotid mass, whether ring in fewer than 5% of patients with parotid masses.5 Suggestive benign or malignant, is an asymptomatic swelling in the preauric- clinical features include (1) the development of a parotid mass in ular or retromandibular region. Occasionally, patients present with a patient with a known history of malignant lymphoma, (2) the metastases to the intraparotid or periparotid lymph nodes. There occurrence of a parotid mass in a patient with an immune disor- are approximately 17 to 20 lymph nodes in the substance of the der (e.g., Sjögren syndrome, rheumatoid arthritis, or AIDS), (3) parotid and along its tail, and there may be a smaller number of the presence of a parotid mass in a patient with a previous diag- lymph nodes within the deep lobe of the gland. These lymph nosis of benign lymphoepithelial lesion, (4) the finding of multiple nodes may be directly affected by metastatic tumors originating masses in one parotid gland or of masses in both parotid glands, from the anterior scalp or the temporal, periocular, or malar and (5) the association of a parotid mass with multiple enlarged regions. Especially with elderly patients, it is extremely crucial to cervical lymph nodes unilaterally or bilaterally.6 obtain a detailed history of any previously excised skin lesions, some of which may have been squamous cell carcinomas (SCCs) Neoplastic Neoplastic masses may be present for years with- that metastasized to the periparotid nodes. Generally, such metas- out causing any symptoms. Benign salivary tumors are more com- tasis involves multiple superficial lymph nodes and presents as dif- mon in younger persons, whereas malignant parotid lesions are fuse enlargement of the parotid parenchyma. With the massive more common in the fifth and sixth decades of life.7 The classic involvement of the parotid gland, facial nerve palsy is not uncom- presentation of a benign parotid tumor is that of an asymptomatic mon in this setting.The majority of metastases to the parotid gland parotid mass that has been present for months to years. Benign derive from cutaneous SCC or melanoma; however, metastatic neoplasms of the parotid include pleomorphic adenoma, basal cell spread from the lung, the breast, and the kidney also is known to adenoma, myoepithelioma,Warthin tumor, oncocytoma, and cystad- occur.13 enoma. The observation of rapid growth in a long-standing pleo- The location of the parotid mass is a very important diagnostic morphic adenoma is suggestive of malignant transformation. In a factor. The classic presentation of a benign mixed tumor is as a 2005 study of 94 patients with pleomorphic adenoma, malignant marblelike lesion in the parotid gland—a firm, mobile mass that transformation to carcinoma was documented in 8.5% of cases.8 commonly originates in the superficial portion of the gland and Rapid tumor growth, metastasis to lymph nodes, deep fixation, generally is not fixed to the deeper structures or to the skin. and facial nerve weakness are all strongly suggestive of malignant Parotid tumors that originate in the deep lobe may present as a disease and are indicators of a poor prognosis.9 Although pain is vague, diffuse swelling behind the angle of the mandible; more more often experienced by patients with benign conditions, it is also often, however, they present as a swelling of the parapharyngeal reported by some patients with infiltrative malignant tumors. In area accompanied by medial displacement of the tonsil or the soft the latter patients, pain is another indicator of a poor prognosis.10 palate. The presence of facial nerve palsy should raise the index of sus- Although physical examination of a parotid mass is a simple picion for malignancy. Occasionally, patients present with classic process in itself, it should be accompanied by a thorough evalua- Bell palsy. This condition is usually of viral origin, and most pa- tion of the head and neck that includes a detailed examination of tients recover over time. If Bell palsy persists, however, further in- the oral cavity and the oropharyngeal, nasopharyngeal, hypopha- vestigation is required, including imaging studies to rule out any ryngeal, and laryngopharyngeal areas. Occasionally, a tumor of the obvious parotid lesion. Facial palsy occurring in association with oropharynx presents as cervical lymphadenopathy or as metastat- parotitis and anterior uveitis is known as Heerfordt syndrome and ic disease in the tail of the parotid. In such cases, it may be diffi- is often seen in patients with sarcoidosis. cult to determine whether the patient has a primary salivary gland tumor or a metastatic lesion. The presence of any suspicious PHYSICAL EXAMINATION pathologic condition in the oropharynx or the base of the tongue The physical examination should focus on the extent of the dis- is an indication for appropriate endoscopy and biopsy of the sus- ease in the parotid, the neck, and the parapharynx; the localized pected primary site. effects of the tumor (including trismus); and the motor or senso- Physical findings suggestive of malignancy include a large and ry deficits resulting from neural invasion. fixed mass, facial nerve weakness, lymph node metastasis, and The mass is palpated to determine whether it is painless or skin involvement; patients with advanced parotid malignancies painful; whether it is soft, firm, hard, or cystic; and whether it is may present with trismus. Whereas patients with benign parotid mobile or fixed to deep tissue or skin.The skin of the scalp, the ear, tumors rarely exhibit facial nerve weakness, approximately 12% and the face is examined for lesions. The neck is palpated for to 15% of patients with parotid malignancies have facial nerve adenopathy. In the oral cavity, the ducts are examined for dis- dysfunction at presentation.14 The most common causes of facial charge or saliva after the glands are milked.The pharyngeal wall is nerve weakness in this setting are adenoid cystic carcinoma, examined for deviation, and the jaw is examined for trismus. poorly differentiated carcinoma, and SCC. Primary SCC of the The parotid occupies a large area, starting from the zygoma and parotid is quite rare, and a diagnosis of SCC in the gland should extending to the upper portion of the neck and behind the lead one to suspect that a tumor has metastasized to the parotid mandible to what is commonly called the tail of the parotid. lymph nodes. Before the diagnosis of primary SCC of the paro- Occasionally, the parotid tissue extends behind the earlobe, in tid is made, high-grade mucoepidermoid carcinoma and metasta- which case it may be misdiagnosed preoperatively as a nonsalivary tic SCC must be excluded. pathologic condition. Accessory parotid tissue is present along The presence of cervical lymph node metastasis may direct Stenson’s duct in approximately 21% of persons.11 Patients some- one’s attention to the parotid mass, though only about 20% of per- times present with a tumor (most commonly, a benign mixed sons with parotid malignancies actually have clinically apparent tumor) of this accessory tissue.12 Attempts to excise such masses cervical lymph node metastases at the time of initial presenta- locally must be avoided, because of the high risk of injury to tion.10 The parotid tumors most commonly associated with branches of the facial nerve. metastatic disease to the lymph nodes at presentation are high-
  4. 4. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 4 grade mucoepidermoid carcinoma, poorly differentiated carcino- uate the ductal arrangements in patients with chronic sialoadeni- ma, and SCC. Lymph node metastases may also derive from high- tis. Currently, however, sialography is rarely used, both because grade adenocarcinomas or malignant mixed tumors. there is a significant possibility of an infectious flare-up and Some patients are totally asymptomatic, with the only signifi- because the study actually yields only minimal information. In the cant physical finding being a mass visible through the open mouth, early 1980s, CT sialography became popular for a time; however, which is suggestive of either a deep-lobe parotid tumor or a para- it was quite a complicated procedure, and clinicians eventually pharyngeal tumor.The majority of parotid tumors develop within found that the information it yielded could easily be obtained from the superficial lobe of the parotid—not surprisingly, given that spiral (helical) CT. Occasionally, surface-coil MRI may be helpful between 80% and 90% of the parotid tissue is superficial to the for evaluating parotid masses deriving from subcutaneous process- facial nerve. However, a significant minority of parotid masses— es. Sialoendoscopy has generated considerable interest, especially about 10%—are found within the deep lobe. Most deep-lobe in Europe and Germany17; however, this sophisticated technology parotid tumors are benign, in which case surgical treatment gen- has not yet entered everyday practice. Although sialoendoscopy erally consists of a superficial parotidectomy with dissection and may be of some value in the assessment of salivary stone disease preservation of the facial nerve, followed by removal of the tumor. or chronic sialectasis, it is rarely performed in the United States at Occasionally, however, malignant deep-lobe parotid tumors do present, and its eventual role in the evaluation of parotid masses occur. Such tumors frequently involve the facial nerve, and surgi- remains to be determined. cal treatment may require sacrifice of the facial nerve in select cir- For a classic benign mixed tumor presenting in the form of a cumstances. Most patients who have undergone surgical treat- small nodule in the superficial lobe of the parotid gland, imaging ment of a malignant deep-lobe tumor will require postoperative is not required. radiation therapy. Currently, the role of positron emission tomography (PET) in the initial evaluation of a parotid mass remains undefined. This modality may, however, be of some value in the evaluation of sus- Investigative Studies pected recurrent parotid cancers, lymph node metastases, or dis- The majority of parotid masses can tant metastases. easily be evaluated with a careful history FINE-NEEDLE ASPIRATION BIOPSY and a thorough physical examination. Nevertheless, it sometimes happens that Routine use of FNA biopsy in the evaluation of a parotid mass even after these measures have been car- [see Table 1] continues to be controversial. One reason for the ried out, there remains some clinical controversy is that cytologic evaluation is difficult. Another is uncertainty regarding whether the patho- that the extent of surgical treatment can easily be defined by logic process is of parotid or of nonsali- means of the clinical assessment. The main argument against vary origin. A number of nonsalivary tumors (e.g., neurofibromas, routine use of FNA biopsy is based on the standard approach to lipomas, lymphadenopathies, metastatic cutaneous lesions, and most parotid masses, which is a superficial parotidectomy that lymphomas) are known to present in the parotid region on occa- includes identification and preservation of the facial nerve. sion. These tumors may be difficult to evaluate clinically, and fur- Nevertheless, FNA biopsy can be quite helpful, especially for the ther diagnostic studies may therefore be required. purposes of preoperative consultation with patients regarding the suspected pathologic process and the extent of surgical ther- IMAGING apy. FNA biopsy has an overall accuracy that exceeds 90%,18,19 Generally, parotid masses are imaged with either computed and it is considered a good investigational tool as long as it is tomography or magnetic resonance imaging.15 CT is superior to used in the appropriate clinical context. MRI for evaluation of the bony structures, whereas MRI may be In the case of a classic benign mixed tumor, which presents as more helpful in distinguishing between inflammatory conditions a mobile, confined, superficial nodule in the parotid gland, FNA and salivary neoplasms. CT scanning is indicated in patients with biopsy is not required for further treatment. However, in cases diffuse enlargement of the parotid gland, tumor extension beyond where the clinical picture is not definitive and one cannot deter- the superficial lobe, facial nerve weakness, trismus, or deep-lobe mine whether the pathologic process is of parotid origin or not, parotid tumors that are difficult to evaluate clinically. If the parotid FNA biopsy is extremely important. Besides distinguishing be- mass appears to be fixed to the deeper structures, it is appropriate tween benign and malignant conditions, FNA biopsy can also to proceed with CT to evaluate the extent and parapharyngeal distinguish between salivary and nonsalivary processes [see Table extension of the disease. MRI is indicated in patients with facial nerve paralysis. Occasionally, it may be necessary to perform both CT and MRI. Both imaging methods are helpful and accurate in distinguishing deep-lobe parotid tumors from other parapharyn- Table 1 Uses of FNA Biopsy in Evaluation geal masses. They are also useful for evaluating suspicious lymph of Parotid Mass nodes and the periphery of the mass (specifically with respect to determining whether the lesion is encapsulated or has irregular To identify suspected malignancy To diagnose metastatic carcinoma borders). To identify suspected lymphoma Ultrasonography can be useful for determining the location of To distinguish between salivary and nonsalivary lesions the lesion and for guiding fine-needle aspiration (FNA) biopsy. In To facilitate conservative management of Warthin tumor or pleomorphic the past, technetium-99m scanning was commonly employed for adenoma in a poor-risk patient the diagnosis of oncocytoma and Warthin tumor.16 To confirm preoperatively suspected malignancy in a patient with facial Various other diagnostic studies are available for evaluation of palsy To evaluate bilateral tumors parotid masses. At one time, sialography was commonly employed to assess patients with suspected salivary stones, as well as to eval-
  5. 5. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 5 Table 2 Salivary and Nonsalivary Pathologic Table 3 American Joint Committee on Processes Distinguished by FNA Biopsy Cancer TNM Clinical Classification of Major Salivary Gland Tumors Benign Mixed tumor TX: Primary tumor cannot be assessed Warthin tumor T0: No evidence of primary tumor Malignant T1: Tumor ≤ 2 cm in greatest dimension without Primary salivary gland cancer extraparenchymal extension Salivary processes Metastatic disease in salivary gland T2: Tumor > 2 cm but ≤ 4 cm in greatest dimen- Cystic adenoma Primary tumor (T) sion without extraparenchymal extension SCC T3: Tumor having extraparenchymal extension Adenocarcinoma without seventh nerve involvement and/or > Melanoma 4 cm but ≤ 6 cm in greatest dimension T4: Tumor invades base of skull, seventh nerve, Lipoma and/or > 6 cm in greatest dimension Sebaceous cyst NX: Regional lymph nodes cannot be assessed Lymph node pathology Nonsalivary processes N0: No regional lymph node metastasis Benign melanoma N1: Metastasis in a single ipsilateral lymph node, Metastatic cancer ≤ 3 cm in greatest dimension Lymphoma N2: Metastasis in a single ipsilateral lymph node, > 3 cm but ≤ 6 cm in greatest dimension; or in multiple ipsilateral lymph nodes, none > 6 cm in greatest dimension; or in bilateral or 2].20 A variety of different lymph node pathologies, benign contralateral lymph nodes, none > 6 cm in parotid tumors, and even suspected malignant parotid tumors Regional lymph nodes (N) greatest dimension can be differentiated by means of FNA biopsy. Furthermore, N2a: Metastasis in a single ipsilateral lymph lymphoepithelial lesions of the parotid, benign mixed tumors, node > 3 cm but ≤ 6 cm in greatest dimension and Warthin tumors are easily diagnosed with this procedure. N2b: Metastasis in multiple ipsilateral lymph FNA biopsy is particularly useful when a parotid mass is likely nodes, none > 6 cm in greatest to be the result of metastasis. dimension Occasionally, in an elderly person whose overall physical con- N2c: Metastasis in bilateral or contralateral lymph nodes, none > 6 cm in greatest dition is poor, a conservative approach can be taken when a dimension Warthin tumor is diagnosed by means of FNA biopsy. Similarly, N3: Metastasis in a lymph node > 6 cm in great- in a person with a long-standing benign mixed tumor, observa- est dimension tion may be appropriate if the patient is not a candidate for sur- MX: Distant metastasis cannot be assessed gical intervention and if FNA biopsy confirms that the lesion is Distant metastasis (M) M0: No distant metastasis benign. M1: Distant metastasis FNA biopsy findings that suggest lymphoma may help one avoid unnecessary parotidectomy and risk to the facial nerve. Often, it is hard to achieve a definitive diagnosis of lymphoma by Staging and Prognosis means of FNA biopsy alone. In such cases, core biopsy or open biopsy can be performed to establish the diagnosis. Core biopsy of For cancers of the parotid gland (as well as those of other major a parotid mass is a difficult procedure (unless the mass is very large salivary glands), staging is accomplished by means of the familiar and very superficial), and it is generally contraindicated on the tumor-node-metastasis (TNM) system developed by the Ameri- grounds that it may cause bleeding or facial nerve injury. Never- can Joint Committee on Cancer (AJCC) and the International theless, if core biopsy can be performed safely, it can be a good Union Against Cancer (UICC) [see Tables 3 and 4].23 choice in cases where lymphoma is suspected on the basis of FNA The prognostic factors in the management of parotid gland biopsy.21 Open incisional biopsy can also be performed safely tumors must be understood in relation to the stage the disease has when done in conjunction with continuous monitoring of the reached, the need for postoperative radiation therapy, and the facial nerve.22 overall long-term outcome [see Table 5]. Such factors include age Benign lymphoepithelial lesions related to HIV disease are readily diagnosed by means of FNA biopsy, especially if they are multiply recurrent cystic lesions in the tail of the parotid or if they Table 4 American Joint Committee on Cancer occur bilaterally. In general, HIV-related pathology is quite easy to Staging System for Major Salivary Gland Tumors diagnose with FNA; HIV-infected patients with benign lym- phoepithelial lesions may be treated by providing appropriate Stage T N M management of the underlying illness. The crucial points for clinicians with respect to FNA biopsy in Stage I T1, T2 N0 M0 the setting of a parotid mass are (1) that this investigative study will not make a definitive diagnosis of parotid malignancy and (2) that Stage II T3 N0 M0 one therefore should not make decisions about how to manage the Stage III T1, T2 N1 M0 facial nerve solely on the basis of an FNA-suggested malignant T4 N0 M0 diagnosis. Any decisions regarding the approach to the facial nerve T3, T4 N1 M0 should also be based on preoperative assessment of facial nerve Stage IV Any T N2, N3 M0 function and intraoperative evaluation of the nerve in relation to Any T Any N M1 the tumor.
  6. 6. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 6 due consideration should be given to the sacrifice and subsequent Table 5 Prognostic Factors for Salivary reconstruction of this structure. Gland Tumors Reconstruction of the facial nerve can be performed with a nerve graft from the greater auricular nerve, from the sural Age at diagnosis Facial nerve dysfunction nerve in the leg, or from the ansa hypoglossi. In view of the Pain at presentation Perineural growth technical complexity of nerve grafting, preoperative consulta- T stage Positive surgical margins tion with a plastic surgeon may be necessary. The functional N stage Soft tissue invasion results of nerve grafting vary considerably, depending on the Skin invasion Treatment type age of the patient, the extent of the disease, and the identifica- tion of and appropriate anastomosis to the peripheral branches of the facial nerve. If postoperative radiation therapy is envi- at diagnosis, pain at presentation, TNM staging, skin invasion, sioned, its potential deleterious effects on nerve regeneration facial nerve dysfunction, perineural growth of the primary tumor, should be kept in mind. positive surgical margins in the final pathology report, soft tissue If the tumor involves only an isolated branch of the facial nerve, invasion by the primary tumor, treatment type, and extranodal one may opt for selective sacrifice of that branch, along with nerve spread of the metastatic disease in the neck. To make definitive grafting. If the tumor extends beyond the parotid gland and decisions regarding treatment, it is necessary to analyze these involves the infratemporal fossa, the ascending ramus of the prognostic factors critically in individual patients. An example of mandible, or the mastoid process, a much more extensive surgical such critical analysis is the prognostic index devised by the Dutch procedure (e.g., composite resection, lateral temporal bone resec- Head and Neck Cooperative Group for patients with parotid can- tion, or radical parotidectomy with sacrifice of the entire facial cer.24,25 In this index, a weighted combination of the parameters of nerve) becomes necessary. Such patients invariably require post- age, pain, tumor size, nodal stage, skin invasion, facial nerve dys- operative radiation therapy [see Radiation Therapy, below]. How- function, perineural growth, and positive surgical margins is ever, in the majority of patients who present with an isolated paro- employed to compute a prognostic score. The score is then used tid mass and a functioning facial nerve, every attempt should be to assign patients to one of four groups, each of which is associat- made to preserve the nerve.26 It is rarely necessary to sacrifice a ed with an expected recurrence-free percentage. functioning facial nerve: the only indication for doing so is a situ- ation in which the entire tumor cannot be resected without sacri- fice of the main trunk or the branches of the facial nerve and there Management is concern about leaving any gross tumor behind. Treatment of a parotid mass depends Intraoperative Frozen-Section Examination on the nature and extent of the lesion [see Table 6]. Malignant parotid masses are The role of intraoperative frozen-section examination in the treated surgically according to established evaluation of a parotid mass, like that of FNA biopsy, is the sub- oncologic principles [see Surgical Therapy, ject of considerable debate. Nevertheless, frozen-section examina- below], with postoperative radiation thera- tion has been found to be useful for distinguishing salivary pro- py added as necessary [see Radiation cesses from nonsalivary processes and benign disease from malig- Therapy, below]. Generally, benign paro- nant disease. In 80% to 90% of cases, the findings from intraop- tid masses are managed surgically as well, with exploration of the erative frozen-section examination correlate with the final patho- parotid gland, evaluation of the neoplasm, and appropriate logic diagnosis.27 This study is also helpful in making a definitive parotidectomy with identification and preservation of the facial diagnosis of Warthin tumor. If frozen-section examination shows a nerve and its branches. In the case of a suspected benign mixed benign mixed tumor and this finding agrees with one’s clinical tumor, enucleation is contraindicated because of the possibility of judgment, lateral superficial parotidectomy should be sufficient. If tumor spillage, incomplete removal of the tumor, injury to the frozen-section examination shows high-grade mucoepidermoid capsule and resultant seeding of the tumor into the parotid tissue, carcinoma, selective neck dissection may be considered (mainly or inadvertent injury to the branches of the facial nerve. Enuclea- for staging purposes, to determine whether any of the deep jugu- tion of such a tumor is very likely to result in local recurrence, which lar nodes are positive). If frozen-section examination provides a invariably is much more difficult to manage than the original definitive diagnosis of malignancy, further decisions about the lesion was and poses a high risk of injury to the facial nerve. extent of parotidectomy and possible selective neck dissection can be made accordingly; if not, the procedure originally planned can SURGICAL THERAPY be performed, with any further interventions (if required) dictated by the final pathologic diagnosis. Obviously, the decision whether Parotidectomy with or without Facial Nerve Reconstruction to sacrifice the facial nerve must not be based solely on whether The minimum surgical procedure for a parotid mass is superfi- the frozen section shows a benign or a malignant process. cial parotidectomy with identification and preservation of the facial nerve [see 2:6 Parotidectomy]. Subtotal parotidectomy may be required for larger tumors that involve the deep lobe of the parotid gland; however, true total parotidectomy with preservation of the Table 6 Principles of Treatment of Parotid Tumors facial nerve is almost impossible, because of the parotid gland tis- Adequate local excision of tumor, based on extent of primary lesion sues surrounding the nerve. If the tumor involves the facial nerve Preservation of facial nerve if possible and is directly infiltrating into it, a diagnosis of malignancy should Elective neck dissection reserved for selected patients be explored, and only if the diagnosis is confirmed should the Postoperative radiotherapy when indicated (in appropriate fields) facial nerve be sacrificed. Preoperative facial nerve weakness gen- Prognosis determined primarily by stage and grade of tumor erally indicates that the tumor is involving the nerve, in which case
  7. 7. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 7 100 Table 7 Indications for Postoperative Radiation Therapy for Parotid Cancer 75 Aggressive, highly malignant tumor Invasion of adjacent tissues outside parotid capsule Percent Regional lymph node metastases Deep-lobe cancer 50 Gross residual tumor after resection Recurrent tumor after resection Invasion of facial nerve by tumor 25 Neck Dissection Overall, about 20% of patients with malignant parotid tumors 0 5 10 present with clinically detectable cervical lymphadenopathy (cN+).10 There is wide agreement that these patients require either Time (Years) a comprehensive or a modified neck dissection [see 2:7 Neck Dissection], depending on the extent of the disease, but there con- Stage I, II Stage I, II with RT tinues to be controversy regarding the management of patients with salivary malignancies who have no clinically detectable cervi- Stage III, IV Stage III, IV with RT cal lymphadenopathy (cN0). In one study, approximately 14% of the patients were in cN+ status; however, approximately 12% were Figure 1 Depicted is the impact of postoperative radiation therapy in cN0 status but presented with pathologically positive nodes (RT) on overall outcome for patients with stage I or II tumors and (pN+).28 In view of the low frequency of occult metastasis in the patients with stage III or IV tumors. group as a whole, the investigators generally did not recommend routine elective treatment of the neck. They did find that certain RADIATION THERAPY histologic grades were associated with a higher incidence of metastatic disease to the neck nodes: the incidence of occult Patients who present with advanced-stage (stage III or IV) dis- metastasis was about 49% in patients with high-grade lesions, ease, a large primary tumor, close margins, perineural spread, soft compared with 7% in those with intermediate-grade or low-grade tissue extension, facial nerve dysfunction, or cervical lymph node lesions. In addition, the incidence of having occult metastatic dis- metastasis invariably require postoperative radiation therapy [see ease was more than 20% in patients with tumors larger than 4 cm, Table 7].31,32 In general, this means that postoperative radiation compared with 4% in those with smaller tumors. therapy is indicated for all patients except those with T1 or T2 The incidence of lymph node metastasis is affected not only by malignant tumors of low-grade histology and clear margins.Thus, the size and histologic grade of the tumor but also by the histologic the decision whether to employ such therapy depends largely on type, the primary tumor stage, the presence of facial nerve palsy, the intraoperative findings and the final pathology report. A 1990 the patient’s age, the extraparotid extension of the disease, and the analysis showed that postoperative radiation therapy had a major degree of perilymphatic invasion.29 In a multivariate analysis, the impact on overall outcome in patients with stage III or IV tumors variables that showed the highest correlation with the incidence of but conferred no statistically significant benefit on patients with lymph node metastasis were the histologic type (i.e., adenocarci- stage I or II tumors [see Figure 1].33 noma, undifferentiated carcinoma, high-grade mucoepidermoid Currently, there is substantial interest in the potential role of carcinoma, SCC, or salivary duct carcinoma) and the T stage.30 neutron therapy as a primary treatment modality for parotid Thus, elective neck dissection may be considered in patients malignancies, especially advanced inoperable parotid cancers and with advanced-stage primary tumors, those whose tumors are of adenoid cystic carcinomas. A group from the University of high histologic grades, and those whose tumors are of certain spe- Washington demonstrated that neutron therapy exerted a benefi- cific histologic types. A selective neck dissection may be performed cial effect when used as the sole treatment of advanced parotid to remove the lymph nodes of the submandibular triangle, level II, cancers.34 Although these results are extremely promising, the level III, and the upper part of level V for the purposes of staging.29 patients treated with this modality clearly experienced an However, a comprehensive neck dissection that encompasses lev- increased incidence of complications. Nevertheless, for patients els I through V may be necessary in patients who present with clin- with inoperable parotid cancer, neutron therapy may be the best ically obvious cervical metastases. option currently available. Discussion Implications of Histopathologic Classification of Parotid World Health Organization.36 The most common types of parotid Gland Cancer tumor are mucoepidermoid carcinoma, adenoid cystic carcinoma, Alhough considerable controversy and debate continue to sur- adenocarcinoma, malignant mixed tumor, acinic cell carcinoma, round the histopathologic classification of malignant parotid and primary SCC [see Figure 2]. tumors, most clinicians currently prefer either the classification As noted (see above), primary SCC of the parotid gland is quite system of the Armed Forces Institute of Pathology35 or that of the rare, and most diagnoses of parotid SCC represent skin cancer
  8. 8. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 2 HEAD AND NECK 2 PAROTID MASS — 8 cystic carcinoma is low; however, the incidence of distant metasta- sis (especially pulmonary metastasis) appears to be high.41 It is noteworthy that even when adenoid cystic carcinoma patients have Other pulmonary metastases, they tend to do remarkably well. Quite often, the metastatic disease in the lungs remains dormant for months or even years. At present, the role of chemotherapy in the Adenocarcinoma management of adenoid cystic carcinoma and parotid tumors is supported only by anecdotal evidence and remains investigational. Mucoepidermoid Principles of Facial Reanimation Adenoid Cystic Every surgeon who performs parotid surgery, especially surgery for parotid cancer, should be familiar with the principles of facial reanimation. If the facial nerve dysfunction is recognized before Acinic the operation, appropriate arrangements may be made for plastic Cell surgical consultation and facial nerve grafting. If the proximal stump of the facial nerve can be identified and the peripheral branches detected at the time of the operation, a nerve graft repair can be performed. The main donor nerves used in facial nerve grafting are the greater auricular nerve, the ansa hypoglossi, and Malignant Mixed the sural nerve. Of these, the greater auricular nerve is the pre- Squamous ferred source for a graft: harvesting is relatively easy, the diameter Figure 2 Shown are the approximate relative frequencies of the matches that of the facial nerve, and the arborization of the distal most common types of parotid gland tumors. branches allows for a greater number of facial nerve grafts.42 The use of loupes or a microscope helps in the placement of the 9-0 nylon stitches employed in facial nerve grafting. that has metastasized to the periparotid lymph nodes. Primary Regeneration of the facial nerve may take 3 to 6 months.There SCC has a high malignant potential, and radical surgical extirpa- is some controversy regarding whether postoperative radiation tion (with preservation of the facial nerve when possible), followed therapy has a beneficial effect on functional outcome after nerve by planned postoperative radiotherapy, is the treatment of grafting: some studies cite detrimental effects,43 whereas others choice.37 report adequate functional outcomes.42,44 In any case, if it is feasi- Mucoepidermoid carcinomas are best divided into low-grade, ble to perform nerve grafting, every attempt should be made to do intermediate-grade, and high-grade tumors.38 For high-grade so. Currently, hypoglossal nerve transfer is rarely performed,45 tumors, selective node dissection may be appropriate, with due because various effective alternatives (e.g., fascia lata slings and consideration given to postoperative radiation therapy. For the Gore-Tex slings) are available. A consultation with a facial plastic majority of low-grade tumors—provided that they are properly surgeon may be quite helpful in the management of patients with excised with appropriate superficial parotidectomy—postoperative total facial nerve palsy. radiation therapy is unnecessary, because the incidence of local One of the most important considerations in addressing facial recurrence is lower than 5%. nerve paralysis is how to prevent exposure keratopathy and other Adenoid cystic carcinoma is a unique salivary gland tumor with ocular complications. Placement of a gold weight or a palpebral a classic Swiss-cheese appearance under the microscope.There is a spring on the upper eyelid may be considered as a primary reha- very high incidence of perineural spread with skip metastasis along bilitative measure aimed at preventing corneal ulceration and the facial nerve and its branches, and the incidence rises with high- opacification.46 In the past, lateral tarsorrhaphy was commonly er T stages.39 The incidence of local recurrence is also very high, employed for this purpose, but currently, as a consequence of the and thus, postoperative radiation therapy should be provided to superior results obtained with the gold weight and the palpebral patients who are at high risk for relapse (i.e., those with close or spring, it is rarely performed. Other, simpler measures for pre- positive margins and those with perineural invasion). Such therapy venting or minimizing ocular complications include the use of arti- appears to reduce the incidence of local recurrence.40 The inci- ficial tears and an eye patch during the day and the use of oint- dence of cervical lymph node metastasis in patients with adenoid ment with proper taping to keep the eyelid closed at night. References 1. Beckhardt RN,Weber RS, Zane R, et al: Minor sali- 5. Batsakis JG: Primary lymphomas of the major sali- 9. Wong DS: Signs and symptoms of malignant pa- vary gland tumors of the palate: clinical and patho- vary glands. Ann Otol Rhinol Laryngol 95:107, rotid tumours: an objective assessment. J R Coll Surg logic correlates of outcome. Laryngoscope 105:1155, 1986 Edinb 46:91, 2001 1995 6. Barnes L, Myers EN, Prokopakis EP: Primary malig- 10. Spiro RH, Huvos AG, Strong EWL: Cancer of the 2. Eneroth CM: Salivary gland tumors in the parotid nant lymphoma of the parotid gland. Arch Otolaryn- parotid gland: a clinicopathologic study of 288 pri- gland, submandibular gland and the palate region. gol Head Neck Surg 124:573, 1988 mary cases. Am J Surg 130:452, 1975 Cancer 27:1415, 1971 7. Kane WJ, McCaffrey TV, Olsen KD, et al: Primary 11. Frommer J:The human accessory parotid gland: its 3. Spiro RH: Salivary neoplasms: overview of a 35- parotid malignancies. A clinical and pathologic re- year experience with 2,807 patients. Head Neck view. Arch Otolaryngol Head Neck Surg 117:307, incidence, nature, and significance. Oral Surg Oral Surg 8:177, 1986 1991 Med Oral Pathol 43:671, 1977 4. Fu YS, Wenig BM, Abemayor E, et al: Head and 8. Friedrich RE, Li L, Knop J, et al: Pleomorphic ade- 12. Rodino W, Shaha AR: Surgical management of Neck Pathology With Clinical Correlations. noma of the salivary glands: analysis of 94 patients. accessory parotid tumors. J Surg Oncol 54:153, Churchill Livingstone, New York, 2001, p 234 Anticancer Res 25:1703, 2005 1993
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