|Year : 2015 | Volume
| Issue : 3 | Page : 652
Adenoid cystic carcinoma of the parotid gland associated with salivary calculi: An unusual presentation
Vijendra S Shenoy, M Panduranga Kamath, Suja Sreedharan, SS Suhas
Department of ENT and Head and Neck Surgery, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
|Date of Web Publication||9-Oct-2015|
Vijendra S Shenoy
Department of ENT and Head and Neck Surgery Kasturba Medical College, Manipal University Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
Adenoid cystic carcinomas (ACC) of the head and neck are relatively rare tumors, consisting of approximately 10-15% of all salivary gland neoplasms. ACC, a slow-growing aggressive malignant tumor of salivary gland commonly seen in the submandibular, sublingual, minor salivary glands is seldom found in the parotid. Calculus, the common cause of salivary gland dysfunction is usually identified in submandibular salivary gland because of its duct anatomy and physiochemical characteristic serous secretion. We report an unusual case of co-existent presentation of ACC with salivary calculi in the parotid gland which is never been reported in the literature. Co-existence of ductal calculi and ACC is rare. Presence of parotid calculus could be due to long standing ductal obstruction by the slow-growing ACC of the parotid or other possibility is that the malignancy could have developed because of chronic irritation by parotid calculi. Confirmatory studies are required to understand its mutual pathological association.
Keywords: Adenoid cystic carcinoma, calculi, parotid
|How to cite this article:|
Shenoy VS, Kamath M P, Sreedharan S, Suhas S S. Adenoid cystic carcinoma of the parotid gland associated with salivary calculi: An unusual presentation. J Can Res Ther 2015;11:652
|How to cite this URL:|
Shenoy VS, Kamath M P, Sreedharan S, Suhas S S. Adenoid cystic carcinoma of the parotid gland associated with salivary calculi: An unusual presentation. J Can Res Ther [serial online] 2015 [cited 2019 Dec 16];11:652. Available from: http://www.cancerjournal.net/text.asp?2015/11/3/652/138001
| > Introduction|| |
Salivary gland tumor constitutes 3-4% of all head and neck neoplasms of which mucoepidermoid and adenoid cystic carcinomas (ACC) are most common, constituting 46% of malignant salivary gland neoplasms.  Sialoliths are calcified structures of varying in sizes that develop within the salivary ductal system, 80-90% found in the submandibular gland, 5-10% in parotid, 0-5% sublingual and other minor salivary glands.  We describe this rare case of coeval existence of salivary calculi in the deep lobe and ACC in the superficial lobe infiltrating to the deep lobe of the parotid gland which is never been reported in the literature.
| > Case REPORT|| |
A 50-year-old male patient presented with a history of swelling in the right side of angle of mandible since 3 months, associated with mild-moderate pain over the swelling. Patient also noted weakness of the right side of face since 1 month. There was no history of increase of swelling during eating.
On examination, 3 × 3 cm non-tender, hard swelling was felt behind and below the right angle of mandible with facial paresis of Grade 2 of House-Brackmann scale [Figure 1]. The fine needle aspiration cytology (FNAC) of the swelling was reported as chronic sialoadenitis. Computerized tomographic (CT) scan showed a calculus in the right parotid gland with inflammatory changes surrounding it [Figure 2]. Complete blood investigation revealed normal.
With provisional diagnosis of chronic sialoadenitis with calculus, the patient was taken up for superficial parotidectomy. Intra-operatively we found calculus in the deep lobe compressing and displacing the main trunk of the facial nerve inferiorly and laterally. Calculus was carefully dissected from the deeper lobe and removed in toto preserving the facial nerve [Figure 3]. The excised specimen was sent for histopathologic examination [Figure 4]. Post-operatively patient was on intravenous antibiotics with analgesics and within a period of 2 weeks facial paresis of the patient recovered completely.
|Figure 1: A 3 × 3 cm non-tender, hard swelling was felt behind and below the right angle of mandible with Grade 2 facial paresis|
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|Figure 2: Computerized tomographic scan showed a calculus in the right parotid gland with inflammatory changes surrounding it|
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|Figure 3: Calculus was carefully dissected from the deeper lobe and removed in toto preserving the facial nerve|
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The histopathology showed foci of neoplasm composed of myoepithelial type of cells arranged in cords, tubules, cribriform and solid pattern with cells surrounded by basophilic myxoid material, which was suggestive of ACC of salivary gland, which was never anticipated. The case was discussed in the tumor board and was posted for total parotidectomy with modified radical neck dissection. As patient and his caretakers were unwilling for the second surgery and further hospital stay, we discharged the patient against medical advice and request.
Patient came back to us after 3 months with recurrent swelling over the right angle of mandible and upper deep cervical lymph node with normal facial nerve function. Fine needle aspiration of lymph node showed metastatic deposits. In view of patient's financial constraints, repeat CT scan was side-lined and was taken up for total parotidectomy and supraomohyoid neck dissection. Intra-operatively facial nerve branches were identified and deep lobe of the parotid with tumor was carefully dissected out. Facial nerve was found to be free of the tumor and thus preserved. Histopathology of the specimen came out to be ACC with cervical lymph node metastasis. Post-operative period was uneventful. After a period of 6 weeks, patient received post-operative radiotherapy of 60 Gy. 3 years later he came with recurrent ulcerating parotid tumor and hemoptysis and was diagnosed to have pulmonary metastasis and soon died of pulmonary complications.
| > Discussion|| |
ACC can occur in any salivary gland, but approximately 50% develop within the minor salivary glands with palate being the most common site of occurrence.  Based on Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, every year 1224 new cases are diagnosed out of which 918 people succumb to death. ACC or cylindroma of the parotid gland is a slow-growing, relentless, and often lethal disease which kills usually by local occurrence and direct extension of the disease. The female to male ratio is approximately 3:2 with a peak incidence between 50 and 60 years of age. The natural history of ACC is characterized by an indolent growth rate, relatively low probability of regional lymph node metastases, and a high likelihood of hematogenous dissemination. ,,, Usually patients present with unilateral slow-growing swelling in the preauricular area. Pain and facial paralysis develop frequently during the course of the disease. The presence of the facial nerve involvement adversely affects the long-term survival. Some authors regard facial nerve involvement as an indication of non-curability. , In our patient, Grade 2 facial paresis observed was secondary to compression and displacement of nerve by the calculus as it completely recovered after removal of calculus. Considering the lesser sensitivity, ultrasonography use in parotid is limited, but occasionally plays a role in guiding needle biopsy. CT scanning and magnetic resonance imaging (MRI) are the diagnostic modalities of choice for imaging parotid neoplasms. Lack of MRI technology in our government based hospital; we opted for CT with contrast. FNAC remains the mainstay of diagnosis, as cytology can clearly distinguish between parotid and non-parotid lesions, benign and malignant lesions. There is no uniform or standard treatment for this disorder. Extensive resection of the parotid gland (including the facial nerve if there is any indication of involvement), followed by external irradiation to the parotid area and upper neck is the most rational approach to the problem. Conservative excisions are oppressed by a high rate of local recurrence. Neck dissection is not included as part of initial therapy unless there are clinically suspicious cervical nodes. ACC's arising from major salivary glands requires surgery with adjunctive radiotherapy. Common indications for post-surgical radiation therapy include tumors >4 cm in greatest diameter, tumors of high grade, tumor invasion of local structures, lymphatic invasion, neural invasion, vascular invasion, tumor present very close to a nerve that was spared, tumors originating in or extending to the deep lobe, recurrent tumors following re-resection, positive margins on final pathology, and regional lymph node involvement. Post-operative radiation is, thus, usually indicated for all parotid malignancies with the exception of small low-grade tumors with no evidence of local invasion or nodal/distant spread.  As for radiation dose; based on AJCC, tumor with positive margins requires 66-70 Gy with neck undissected 50-54 Gy and neck dissected 60-63 Gy. Chemotherapy has not shown effective as single modality therapy and is generally reserved for the palliative treatment of symptomatic locally recurrent or metastatic disease that is not amenable to further surgery or radiation. 
Parotid calculi are less common than calculi in the submandibular gland because the former is primarily serous. The patient presents with swelling and pain, aggravated by eating, but subsiding within the next hour or so after the meal. Plain X-rays may reveal larger stones, but the superimposed soft-tissue image of the cheek, makes this method less suited for the detection of smaller ones. Sialograms can reveal calculi but are difficult to interpret. Stones close to the duct orifice are removed by ductal dilation and massage. Those in the gland are treated by excising the gland. 
Ours was an unusual case because of simultaneous presentation of ACC in the superficial lobe and sialolith in the deeper lobe. ACC is the most common tumor of submandibular and minor salivary glands and constitutes only 2% of parotid neoplasm. Based on tumor architecture it can be grouped into three histologic subtypes-cribriform, tubular and solid. The tubular variety has best prognosis. ACC usually exhibits a protracted course characterized by an indolent growth pattern and a relentless tendency for local recurrence and perineural invasion. This neurotropic tendency is characteristic of ACC and has been reported to occur in 20-80% of patients. Lymphatic spread of ACC is unusual. 17% incidence has been reported. Distant metastasis most frequently occurs in the first 5 years usually to lungs. At 5-year survival of 73-75% has been reported. The development of metastases is independent of local recurrence. Metastasis to bone is rapid and aggressive than pulmonary metastases, which may remain asymptomatic. When the tumor is localized, particularly to the superficial lobe, careful total parotidectomy with preservation of the facial nerve is performed; neck dissection is only performed in the presence of obvious lymph node involvement. Post-operative irradiation is not systematically indicated.
| > Conclusion|| |
Adenoid cystic cancer is a rare tumor with a high propensity to recur in the primary area, metastasize to new organs with perineural spread. Hence, early identification is justified. ACC of parotid itself is a unique with little understood etiology, and the coexistence of ductal calculi and ACC of parotid is much rarefied with deficient reported cases; confirmatory studies are required to understand the mutual pathological association of calculi and carcinoma.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]