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Diagnosis and Treatment of Accessory Parotid Gland Tumors
Abstract
The accessory parotid gland is a small unit of salivary gland tissue separated from the main parotid gland and lying on the masseter muscle. The accessory parotid gland is not rare, but accessory parotid gland tumors are rare. Accessory parotid gland tumors are associated with a higher rate of malignant tumors than are the main parotid glands, because the accessory parotid gland is made up of a fairly equal percentage of mucinous and serous acinar units in contrast to the predominant serous composition of the main parotid gland, as is the submandibular gland. Herein, we describe the diagnosis and treatment of accessory parotid gland tumors.
... Nevertheless, as many neoplasms are of lower malignancy, thorough follow-ups over time are important to observe the development. 26 As in the main PG, pleomorphic adenoma remains the most common benign tumor of the APG. 2,5,6,18 In spite of its benign features, primary and recurrent pleomorphic adenomas are rarely but notably observed to progress to carcinoma ex pleomorphic adenoma, yielding a strong metastatic tendency with a high mortality. ...
... Here, it is crucial to properly identify and excise the structure with appropriate margins to avoid recurrences, as well as choosing an approach where complete preservation of adjacent structures is attainable. 7,[26][27][28][29] Considering the anatomy, Stensen duct serves as a bridge between the APG and the PG, indirectly connecting the 2 with several additional tributaries from the APG occasionally emptying into it. 1 This characteristic makes the APG a notable factor when also treating PG tumors by the means of performing a parotidectomy. ...
Purpose:
The accessory parotid gland is a collection of salivary tissue separate from the main parotid gland. When present, it may complicate parotidectomies, promote parotitis, and serve as a potential site for benign and malignant lesions to arise. The aim of this study was to provide a comprehensive and current overview of the anatomy of the accessory parotid gland, as there is a wide discrepancy in the literature regarding its prevalence.
Materials and Methods:
The authors conducted a search in PubMed, Embase, ScienceDirect, Web of Science, SciELO, BIOSIS, Current Content Connect, Korean Journal Database, and Russian Citation Index to identify all studies which reported relevant data on the accessory parotid gland, with no date or language restrictions applied. Data on prevalence, side of occurrence, and sex dimorphism of the accessory parotid gland were extracted and pooled into a meta-analysis.
Results:
A total of 13 articles (n = 3115 subjects) were included in the study. The results revealed that the overall pooled prevalence of an accessory parotid gland was 32.1% (95% confidence interval: 21.2–44.0). It was more prevalent in cadaveric studies (35.8%) than in computed tomography studies (21.5%), had a higher prevalence in Asia (33.8%) as compared to North America (23.5%), and when present, it was most often found as an unilateral structure (77.8%).
Conclusions:
With respect to the findings presented, the accessory parotid gland may be considered an anatomical variation likely to encounter in the population. More anatomical studies on the structure and its prevalence are needed, in all regions of the world, to provide a representative global overview.
Background : An accessory parotid gland (APG) is a common anatomical structure that occurs in 10%–56% of individuals. Pleomorphic adenomas are the most common benign tumors of the APG, and their ideal treatment is surgical excision, although there is a risk for aesthetic disorders and facial nerve damage due to the site of origin. Moreover, despite being benign, these tumors are known to recur. Therefore, it is necessary to achieve both reliable excision and avoidance of facial nerve damage. Case presentation : We report a case of a 49-year-old Japanese man with a mass in his left cheek. The lesion was diagnosed as a benign salivary gland tumor derived from the APG by computed tomography imaging, magnetic resonance imaging and fine needle aspiration cytology. We resected the tumor using modified high submandibular incision under the endoscopic-assisted field of view. Discussion and Conclusions : The tumor was less invasive and reliably resected using an endoscope. In surgical treatment, the endoscopic-assisted technique is very useful to achieve complete tumor resection and prevent relapse while avoiding serious complications due to surgical procedures. J. Med. Invest. 68 : 376-380, August, 2021
The accessory parotid gland is salivary tissue separated from the main parotid gland and lying on masseter muscle. It has secondary duct emptying into the Stensen's duct. The accessory parotid gland exists in 21-61% of individuals. However, the appearance of an accessory parotid tumor is rare, with a reported frequency of 1-7.7% of all parotid gland tumors. Carcinoma ex pleomorphic adenoma arises from a pre-existing benign mixed tumor. Most of these tumors will have malignant epithelial component, but not malignant stromal component. Reports of Fine Needle Aspiration Cytological (FNAC) diagnosis of malignant mixed tumor are uncommon and have been limited to cases arising in the parotid. We report a case of carcinoma ex pleomorphic adenoma of the accessory lobe of the parotid, and address the cytopathology features and pitfalls of this condition.
A 73 aged female presented with a right nontender midcheek mass. The lesion had been present 18 months, with a recent increase in size. FNA was performed and the smears demonstrated features indicative of pleomorphic adenoma admixed with findings indicative of a poorly differentiated carcinoma.
FNAC can accurately diagnose carcinoma ex pleomorphic adenoma when strongly fixed requirements are implemented.
Accessory parotid lesions are clinically rare and its management remains poorly understood. The aim of this study was to analyze the clinical management of accessory parotid lesions.
From April 1999 to November 2008, a retrospective analysis of 32 patients with accessory parotid lesions was performed. The preoperative examinations, surgical treatment, and prognosis were recorded and analyzed.
Among the 32 patients, there were 8 men and 24 women with an overall average age of 45 years. These patients always presented without obvious symptoms, and the masses were moderate to hard in hardness without tenderness, mobile, and with clear boundary. The pathologic diagnoses were 24 benign and 8 malignant lesions. Surgery and surgery plus radiotherapy were performed in the patients with benign and malignant lesions, respectively, with good prognosis.
Accessory parotid lesions are rare, and the clinical manifestation is always the same for benign tumors. Surgical resection and surgical resection plus radiotherapy are the primary choices of treatment for benign and malignant lesions, respectively. The prognosis is always good.
Primary adenocarcinomas of the parotid gland are rare and account for less than 5% of all head and neck malignant neoplasms. There is considerable variation in biological behaviour within this group; low-grade tumours exhibit slow growth rates with minimal or no local invasion. High-grade tumours, however, show a high incidence of local recurrence and distant metastasis.
The purpose of this paper is to analyse the important prognostic indicators for this cancer.
A systematic review was performed involving 19 published studies from 1987 to 2005 which included 4631 patients. T stage, grade of tumour, N stage and adjuvant radiotherapy on overall (5 year) survival were analysed as prognostic indicators.
T stage (p=0.041, hazard ratio 1.8 (confidence interval 1.2-2.9)), N stage (p=0.05, hazard ratio 1.1 (0.2-1.8)), and high-grade (p=0.001, hazard ratio 2.1 (1.5-2.7)) were associated with a significantly worse survival. The effect of adjuvant radiotherapy was to improve overall survival: p=0.002, hazard ratio 2.9 (1.5-4.7). The mean 5 year survival for advanced high-grade parotid cancer was 35%.
High-grade advanced parotid cancers are associated with a poor survival. Adjuvant radiotherapy is indicated in these tumours and this improves survival.
An accessory parotid gland occurs in approximately 21 percent of human subjects. It is located anterior to the main parotid gland, usually just above Stensen's duct and connected by its own duct to the latter. Any lesions that can occur in the main parotid gland can also arise in an accessory parotid gland. For the excision of lesions of the accessory parotid gland, we prefer to turn the same cervicofacial flap used for a lateral or total parotidectomy. This permits one to fully visualize the superficial and deep main parotid segments, the trunk and the branches of the facial nerve, and the accessory parotid gland along with its duct system and Stensen's duct.
A summary is presented of our experience with 23 patients who had accessory parotid tumors, comprising 1% of all primary parotid neoplasms seen during a 40 year period. Although more than half of the tumors proved malignant, adequate excision was usually curative. We prefer to approach these tumors through an extended cheek-flap incision. Once the lesion is exposed, either local excision or resection in conjunction with subtotal parotidectomy can be performed, depending on the clinical findings.
Tumors of the accessory parotid apparatus and other lesions of the soft parts of the cheek can be adequately removed through a preauricular hockey stick incision with the development of an anterior cheek flap and with preservation of the parotid gland.This approach permits satisfactory removal of these lesions with adequate protection of the facial nerve and Stensen's duct.This was accomplished in twenty patients resulting in an improved cosmetic result, lessened morbidity, and decreased surgical time.
The parotid glands of 228 Japanese human cadavers were examined to determine the incidence and histological features of accessory parotid glands. The incidence was found to be 56% with no differences between right and left sides or between sexes. Thirty parotid glands and their associated accessory glands were examined histologically: eight of these accessory glands were found to be mixed secretory glands (i.e., containing both serous and mucous acini). Thus, the pattern of differentiation of a significant fraction of accessory glands differs from that of the main parotid gland: it appears that mixed acini, present in the early stages of development, persist into later life, and their presence may be related to tumors developing at these sites.
A rare case of a 9-year-old female with mucoepidermoid carcinoma arising in the accessory parotid gland is reported. She had complained of a painless and round mass of the left cheek for a duration of 14 months. Sialography, ultrasonography, CT scan and MRI were performed preoperatively. Sialography revealed a small duct separating from the Stensen's duct. CT and MRI showed that the tumor with smooth outline was lying on the masseter muscle and detached from the main parotid gland. The preoperative diagnosis was an accessory parotid gland tumor. The tumor was removed without facial nerve injury via standard parotidectomy incision. The tumor was composed of mucous and epidermoid cells. The pathological diagnosis was low-grade mucoepidermoid carcinoma.
Three cases of accessory parotid gland lesions are reported. The literature concerning accessory gland disease and its diagnosis and treatment is reviewed.