Malignant Transformation of Chronic Nonspecific Sialadenitis: A Rare Clinical Presentation
Corresponding Author: Rajiv C Michael, Department of Head and Neck Surgery, Christian Medical College, Vellore, Tamil Nadu, India, Phone: 04162282075, e-mail: firstname.lastname@example.org
How to cite this article Ashish G, Michael RC. Malignant Transformation of Chronic Nonspecific Sialadenitis: A Rare Clinical Presentation. Int J Head Neck Surg 2021;12(1):31–33.
Source of support: Nil
Conflict of interest: None
A 26-year-old man presented with a large, painless, mobile, pedunculated, fluctuant, and nontransilluminant swelling hanging in front of the left ear. He had undergone superficial parotidectomy 9 months ago elsewhere for chronic nonspecific sialadenitis of left parotid gland. The fine needle aspiration was nondiagnostic and revealed turbid dark yellow color fluid. A total parotidectomy was performed to remove the lesion completely as the tumor was involving the deep lobe. Histopathology was consistent with features of low-grade mucoepidermoid carcinoma. Immediate postoperatively the patient had a House and Brackman grade III left facial nerve paresis, which later improved to grade II. This unusual presentation of malignant transformation of chronic nonspecific sialadenitis is one of the rare unique reported cases to our knowledge.
Keywords: Cyst, Mucoepidermoid carcinoma, Nonspecific sialadenitis, Parotid..
Parotid gland tumors can be of varied sizes and presentation. Various forms of chronic sialadenitis can predispose its malignant transformation over a long period of time. Entities such as Kuttner tumor and lymphomas have been associated with chronic sialadenitis of parotid glands.1
Clinical examination of such lesions should be coupled with investigations such as MRI as well as histopathological correlation by fine needle aspiration cytology (FNAC). Depending on the histopathology of the tumor, the treatment of choice may extend from superficial parotidectomy to total parotidectomy with or without adjuvant therapy.2 Therefore, long-term follow-up of such patients with nonspecific sialadenitis is warranted and any suspicion of malignant transformation should prompt the treating surgeon for a detailed workup.
A 26-year-old gentleman had been diagnosed with chronic nonspecific sialadenitis of the left parotid gland for which he underwent a superficial parotidectomy in 2009 elsewhere. He was asymptomatic for 9 months after surgery. He then noticed a small swelling behind the left ear lobule, which was initially the size of a peanut, then gradually increased in size and attained the present size. He gives no history of pain, difficulty in swallowing, or difficulty in breathing. He has no other comorbidities.
On examination, a scar was seen at the left parotid region (previous parotidectomy incision scar). A 9 × 8 × 4 cm infra-auricular swelling was seen arising from the left parotid region (Fig. 1). The mass had a varied consistency. Transillumination was absent.
MRI T1 suggested a large hyperintense (Fig. 2) cystic lesion [83 × 72 × 50 mm (CC × AP × TR)]—from the infra-auricular left parotid gland region (Fig. 2), with extensive tortuous linear channels (measuring 5–8 mm) within it (Fig. 3). The facial nerve was noted along the medial margin of the deep lobe before it divides into the parotid gland (Fig. 4).
He underwent a conservative total parotidectomy. A large tumor with pedunculated component (10 × 10 cm) with infiltration into the deep lobe of the left parotid gland was found (Fig. 5). There was extensive scar tissue with no planes between the tumor, surrounding soft tissue, masseter muscle, and the left external ear canal. The tumor was abutting the upper division of the facial nerve. Main trunk and upper division of the facial nerve were identified and preserved. He had an uneventful postoperative period and was shifted to the ward. Postoperatively, he was found to have developed a grade III left-sided House and Brackman facial nerve paresis. He was given appropriate facial physiotherapy and eye protective measures.
The histopathology was consistent with features of low-grade mucoepidermoid carcinoma with no perineural invasion.
Grossly, the specimen measured 9 × 6 × 3.5 cm. Sectioning revealed a tumor with cystic and solid cut surfaces. The cystic cavity measured 7 × 8 × 3.5 cm and was filled with green gelatinous material.
He was given adjuvant radiotherapy (66 Gy in 33 fractions) and he tolerated the radiotherapy well. There was no evidence of recurrence or residual of disease at 2-year postoperative status. His facial palsy has downgraded from grade III to grade II presently. This seems to be a rare case report, suggesting malignant transformation of biopsy-proven nonspecific sialadenitis in parotid gland.
Chronic nonspecific parotid sialadenitis is known to cause intermittent bouts of parotid pain and swelling, reduced salivary flow, mucopurulent secretion, and is an inflammatory condition.
The etiopathogenesis could be attributed to reduced salivary secretion leading to accent of bacterial flora along the ductal system leading to infection. This ultimately causes destruction and fibrosis of the acinar elements and duct ectasia. Mostly cases are idiopathic; however, in some cases it may be due to obstruction of the ducts. Obstruction may be secondarily due to stones, duct strictures, or external pressure on the main duct.3
The other theory proposed suggests that repeated episodes of acute infection may lead to mucus metaplasia of ductal epithelium resulting in increased mucus content of secretions, stasis, and further episodes of inflammation.4
Elaborate battery of investigations ranging from sialography, contrast-enhanced CT scan, FNAC, ultrasonography, and contrast-enhanced MRI scans are employed for this condition.5
Majority of these are successfully managed with conservative therapy, which includes antibiotics, analgesia, mouthwashes, sialogogues, and gland massage. Recurrent episodes lead to parenchymal fibrosis and irreversible ductal damage leading to a fibro-inflammatory mass; such resistant cases are managed surgically (both superficial and near-total parotidectomy have been advocated).6,7
Superficial parotidectomy is esthetically more acceptable as compared to radical surgery and there is evidence that it also allows preservation of residual function.8
Malignant transformation of this entity has been very rarely described.
Stewart et al. in 1945 first described a separate salivary neoplasm recognized as mucoepidermoid carcinoma.9 Pluripotent reserve cells of the excretory ducts of salivary gland, which have the potential to differentiate into squamous, columnar, and mucous cells, are believed to be responsible for it.10
Although no specific etiologic factors have been identified, exposure to ionizing radiation has been reported in some cases. Mucoepidermoid carcinoma accounts for 5% of all salivary gland tumors. It most commonly involves the parotid gland and is the most common malignant tumor to arise in children and adolescents under 20 years of age. It initially presents as a painless mass 2–3 cm in diameter. Consistency may vary from firm to hard, and very rarely cystic in nature.11
Histologically, mucoepidermoid carcinoma consists of combination of squamous and mucous cells arranged in cords, sheets, or cystic configuration and are classified as low, intermediate, or high grade.12 Low-grade variety is treated surgically with local wide block excision and wide block excision with radical neck dissection for high-grade variety.13
Radiotherapy should be used in cases where the deep lobe is involved or where adequate surgical margins are not tumor free; however, these cases need to be periodically followed up.14
The prognosis of mucoepidermoid carcinoma depends on the clinical stage and histological grade. Low-grade mucoepidermoid carcinoma has a better 5-year survival rate from 92 to 100% as compared to high-grade mucoepidermoid carcinoma with 0–43% 5-year survival rate. Lymph node involvement ranges from 18 to 28%.12,15
Mucoepidermoid carcinoma of the parotid is a rare salivary gland tumor. Clinical stage and histological grade are the main prognostic factors. Its presentation as a cystic mass is very rare. As a conclusion, malignant transformation of nonspecific sialadenitis of the parotid gland has not been reported earlier to the best of our knowledge.
3. Baurmash HD. Chronic recurrent parotitis: a closer look at its origin, diagnosis, and management. J Oral Maxillofac Surg Off J Am Assoc Oral Maxillofac Surg 2004;62(8):1010–1018. DOI: 10.1016/j.joms.2003.08.041.
4. British Journal of Plastic Surgery [Internet]. [cited 2013 Sep 12]. Available from: http://www.journals.elsevierhealth.com/periodicals/ybjps/article/S0007-1226(97)90135-1/references.
8. Amin MA, Bailey BM, Patel SR. Clinical and radiological evidence to support superficial parotidectomy as the treatment of choice for chronic parotid sialadenitis: a retrospective study. Br J Oral Maxillofac Surg 2001;39(5):348–352. DOI: 10.1054/bjom.2001.0671.
9. Baker SR, Malone B. Salivary gland malignancies in children. Cancer 1985;55(8):1730–1736. DOI: 10.1002/1097-0142(19850415)55:8<1730::AID-CNCR2820550819>3.0.CO;2-J.
11. Brandwein MS, Ivanov K, Wallace DI, et al. Mucoepidermoid carcinoma: a clinicopathologic study of 80 patients with special reference to histological grading. Am J Surg Pathol 2001;25(7):835–845. DOI: 10.1097/00000478-200107000-00001.
14. Rahbar R, Grimmer JF, Vargas SO, et al. Mucoepidermoid carcinoma of the parotid gland in children: A 10-year experience. Arch Otolaryngol Head Neck Surg 2006;132(4):375–380. DOI: 10.1001/archotol.132.4.375.
© The Author(s). 2021 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.