|Year : 2022 | Volume
| Issue : 1 | Page : 52-54
Polymorphous adenocarcinoma of the parotid – An uncommon site of occurrence
Prabhat Mahato, Chhanda Das, Ankita Pranab Mandal, Madhumita Mukhopadhyay
Department of Pathology, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
|Date of Submission||24-Sep-2021|
|Date of Decision||22-Jan-2022|
|Date of Acceptance||23-Jan-2022|
|Date of Web Publication||30-Mar-2022|
Dr. Ankita Pranab Mandal
Flat No. B501, Gulmohar II CHS Ltd, Plot No. 13, Sector-42, Seawood, Nerul - 400 706, Navi Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Polymorphous low-grade adenocarcinoma is a neoplasm of the minor salivary glands and is malignant in origin but is indolent in nature. Currently, this neoplasm is documented and known as polymorphous adenocarcinoma (PAC) by WHO Classification of Salivary Gland Tumors (2017). Of all the salivary neoplasms, minor salivary gland neoplasm accounts for 9%–23%. Very rarely, it involves major salivary glands such as parotid, submandibular, and sublingual in <5% cases. It may develop either de novo or from pleomorphic adenoma. PAC mimics some benign as well as malignant neoplasms. Histopathological features alone cannot diagnose PAC due to the overlapping features with other neoplasms, and so immunohistochemistry is essential to confirm the diagnosis and hence aids in the proper management of PAC. We report a case of PAC arising from parotid gland in a 52-year-old male treated with facial nerve preservation.
Keywords: Immunohistochemistry, parotid, polymorphous adenocarcinoma, salivary gland
|How to cite this article:|
Mahato P, Das C, Mandal AP, Mukhopadhyay M. Polymorphous adenocarcinoma of the parotid – An uncommon site of occurrence. Int J Adv Med Health Res 2022;9:52-4
|How to cite this URL:|
Mahato P, Das C, Mandal AP, Mukhopadhyay M. Polymorphous adenocarcinoma of the parotid – An uncommon site of occurrence. Int J Adv Med Health Res [serial online] 2022 [cited 2022 Aug 8];9:52-4. Available from: https://www.ijamhrjournal.org/text.asp?2022/9/1/52/341341
| Introduction|| |
Polymorphous low-grade adenocarcinoma (PLGA) is a neoplasm of the minor salivary glands and is malignant in origin but is indolent in nature. Of all the salivary neoplasms, minor salivary gland neoplasm accounts for 9%–23%. In 1983, PLGA was first labeled as terminal duct carcinoma by Batsakis et al. and lobular carcinoma by Freedman et al. Currently, this neoplasm is documented and known as polymorphous adenocarcinoma (PAC) by WHO Classification of Salivary Gland Tumors (2017).,, Wide limited local excision is the choice of treatment for PLGA.,,,,, We report a case of PAC arising from parotid gland which was treated with facial nerve preservation.
| Case Report|| |
A 52-year-old male presented with right preauricular painless swelling, progressively increased in size for a period of 5 years. On clinical examination, swelling was firm and nontender. He underwent contrast-enhanced computed tomography of face and neck which revealed a well-defined cystic lesion with few thick enhancing septa and solid irregular mural nodules in the superficial lobe of right parotid gland [Figure 1]a. Magnetic resonance imaging showed 7 cm × 5 cm × 5 cm heterogeneously enhancing solid cystic hyperintense altered signal intensity lesion in superficial lobe of right parotid gland, obliterated fat planes with masseter muscles and ramus of mandible, extending superiorly up to preauricular region. Fine-needle aspiration was performed from the swelling, and the cytomorphological features were suggestive of a cystic lesion of the salivary gland, having atypia of undetermined significance, Milan category III.
|Figure 1: (a) Computerized tomography scan shows large well-defined SOL (b) Gross specimen (c) Section shows tumor mass arranged in tubular and papillary pattern (×100, H and E) (d) Section shows atypical tumor cells with pleomorphic vesicular nuclei, prominent nucleoli and nuclear grooving (×400, H and E)|
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The lesion was surgically excised through right superficial parotidectomy with facial nerve preservation. Grossly, the lesion was well-circumscribed measuring 6 cm × 5 cm × 4 cm. On cut open, whitish homogenous area was noted with cystic spaces in between [Figure 1]b. Histologically, the section showed tumor mass composed of neoplastic cells arranged in branching tubular and somewhere in papillary pattern [Figure 1]c. Lining cells were highly atypical with pleomorphic vesicular nuclei and prominent nucleoli [Figure 1]d. Nuclear grooving was noted. Intraluminally, eosinophilic secretions were also seen. Neither perineural invasion nor vascular invasion was seen. Lymphoid aggregates and hemorrhages were also seen. The histopathological features were consistent with PAC. The eosinophilic secretions were periodic acid–Schiff positive. Immunohistochemical examination was performed by peroxidase-antiperoxidase technique using cluster of differentiation (CD) 117 (monoclonal mouse antibody; clone: EP10, positive control: testis, and cytoplasmic/membranous staining), cytokeratin 7 (CK7) (monoclonal mouse antibody; clone: OVTL12/30, positive control: lung, and cytoplasmic/membranous staining), p63 (monoclonal mouse antibody, clone: 4A4, positive control: specimen of prostate; and nuclear staining), and S100 (polyclonal rabbit antibody; clone: 15E2E2, positive control: melanoma, and cytoplasmic staining). Tumor cells showed strong and diffuse positivity to S100 [Figure 2]a. Tumor cells also showed positivity to CK7, p63, and CD117 [Figure 2]b, [Figure 2]c, [Figure 2]d. These immunohistochemical findings confirmed the diagnosis of PAC which differentiates it from pleomorphic adenoma and adenoid cystic carcinoma.
|Figure 2: (a) Immunohistochemistry staining for S100 showing positivity (×400) (b) Immunohistochemistry staining for CK7 showing positivity (×400) (c) Immunohistochemistry staining for p63 showing positivity (×400) (d) Immunohistochemistry staining for CD117 showing positivity (×400)|
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| Discussion|| |
Salivary gland tumors are very unusual. Of all the head-and-neck neoplasms, it comprises 2%–6.5% affecting mainly major salivary glands, particularly the parotids. PAC is a distinct neoplasm illustrated by architectural variety, cytological regularity, and clinically painless and slow-growing. Mucoepidermoid carcinoma is the most common minor salivary gland malignancy followed by PAC.
Palate (49%–77.8%) is the most common site of origin of PAC, followed by buccal mucosa or upper lip (7.4%–13.4%).,, It may also involve the tongue, floor of the mouth, alveolar ridge, and lower lip. Very rarely, it involves major salivary glands such as parotid, submandibular, and sublingual in <5% cases. Furthermore, it is also seen in other sites like breast, vagina, lung., PAC is mainly seen in adult patients from 3rd to 7th decades with a highest incidence from 5th to 6th decades of life. It occurs most commonly in females than in males. Some reports have suggested that it arises de novo or as neoplasms developing in a preexistent pleomorphic (carcinoma ex pleomorphic adenoma)., In this report, PAC developed de novo in the parotid gland. Surgical excision either superficial or deep parotidectomy is the treatment of choice. Macroscopically, it is well-circumscribed, nonencapsulated, and firm. Microscopically, architectural patterns are solid, trabecular, glandular, spindled, fascicular, ductal, and cystic. Tumor cells are cuboidal to columnar with eosinophilic cytoplasm and enlarged nucleoli with mucoid to hyaline stroma.
Immunohistochemical staining aids in the diagnosis of PAC, as tumor cells stain positive with S100, Epithelial membrane antigen (EMA), and CK7. p63 also stains positive., In this report, PAC showed positivity to CD117, CK7, p63, and S100. Pleomorphic adenoma, monomorphic adenoma, and adenoid cystic carcinoma share the histologic characteristics as PAC, so they are considered the differential diagnosis. Lack of infiltration is seen in pleomorphic adenoma and monomorphic adenoma and pleomorphic adenoma presents with chondromyxoid matrix so they can be distinguished from PAC but they have the propensity for perineural invasion. Pleomorphic adenoma stains are positive for glial fibrillary acidic protein, but PAC is negative. Adenoid cystic carcinoma shows histologic patterns such as cribriform, tubular and solid, and exhibit basaloid cells with scant cytoplasm, PAC illustrates some spindling. PAC shows strong diffuse positivity S100 and EMA while adenoid cystic carcinoma stains much less diffusely. Low-grade papillary adenocarcinoma (LGPA) is also considered a differential for PAC. However, LGPA demonstrates a more aggressive behavior, and the rate of local recurrence and regional lymph node metastasis are higher.,
PAC is associated with PRKD1 mutations and adenoid cystic carcinoma shows MYB or MYBL1 gene rearrangements. These genetic abnormalities are pathognomonic of the tumors and can also be useful in the differential diagnosis. We were not able to perform genetic studies because of financial constraints. PAC sometimes erodes the underlying bone and may even show perivascular or perineural invasion. Metastases are very rare and even if present is mostly restricted to the regional lymph nodes.
Wide limited local excision is the choice of treatment approach. If tumor is seen at surgical margin, then postoperative radiotherapy is suggested. Adjuvant radiotherapy and radical surgical excision are recommended in cases of cervical metastases. In recurrent cases, radical surgery is done.,,, In this case report, no metastasis was identified and was treated surgically with facial nerve preservation that is superficial parotidectomy.
| Conclusion|| |
PAC is a tumor of minor salivary gland but it may also arise in the major salivary gland which may develop either de novo or from pleomorphic adenoma. PAC has an indolent behavior and may mimic a benign neoplasm, so a thorough examination of the entire surgical specimen should be done. Histopathological features alone cannot diagnose PAC due to the overlapping features with other neoplasms, and so immunohistochemistry is essential to confirm the diagnosis and hence aids in the proper management of PAC.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Freedman PD, Lumerman H. Lobular carcinoma of intraoral minor salivary gland origin. Report of twelve cases. Oral Surg Oral Med Oral Pathol 1983;56:157-66.
Ito FA, Ito K, Vargas PA, de Almeida OP, Lopes MA. Salivary gland tumors in a Brazilian population: A retrospective study of 496 cases. Int J Oral Maxillofac Surg 2005;34:533-6.
Batsakis JG, Pinkston GR, Luna MA, Byers RM, Sciubba JJ, Tillery GW. Adenocarcinomas of the oral cavity: A clinicopathologic study of terminal duct carcinomas. J Laryngol Otol 1983;97:825-35.
Seethala RR. Update from the 4th
edition of the world health organization classification of head and neck tumours: Preface. Head Neck Pathol 2017;11:1-2.
Gupta S, Kumar CA, Raghav N. Polymorphous low-grade adenocarcinoma of the palate: Report of a case. Indian J Cancer 2011;48:518-9.
] [Full text]
Seethala RR, Johnson JT, Barnes EL, Myers EN. Polymorphous low-grade adenocarcinoma: The University of Pittsburgh experience. Arch Otolaryngol Head Neck Surg 2010;136:385-92.
Khosla D, Verma S, Gupta N, Punia RS, Kaur G, Pandey AK, et al.
Polymorphous low grade adenocarcinoma of the parotid in a teenager. Iran J Otorhinolaryngol 2017;29:299-302.
Olusanya AA, Akadiri OA, Akinmoladun VI, Adeyemi BF. Polymorphous low grade adenocarcinoma: Literature review and report of lower lip lesion with suspected lung metastasis. J Maxillofac Oral Surg 2011;10:60-3.
Metin M, Dogan S, Yazici H, Soy FK, Dilci A, Avcu M, et al
. Polymorphous low grade adenocarcınoma of hard plate. J Transl Sci 2018;4:1-3.
Eveson JW, Cawson RA. Tumours of the minor (oropharyngeal) salivary glands: A demographic study of 336 cases. J Oral Pathol 1985;14:500-9.
Evans HL, Batsakis JG. Polymorphous low-grade adenocarcinoma of minor salivary glands. A study of 14 cases of a distinctive neoplasm. Cancer 1984;53:935-42.
Buchner A, Merrell P, Carpenter W. Relative frequency of intraoral minor salivary gland tumors: A study of 380 cases from northern California and comparison to reports from other parts of the world. J Oral Pathol Med 2007;36:207-14.
Castle JT, Thompson LD, Frommelt RA, Wenig BM, Kessler HP. Polymorphous low grade adenocarcinoma: A clinicopathologic study of 164 cases. Cancer 1999;86:207-19.
Xu B, Aneja A, Ghossein R, Katabi N. Predictors of Outcome in the Phenotypic Spectrum of Polymorphous Low-grade Adenocarcinoma (PLGA) and Cribriform Adenocarcinoma of Salivary Gland (CASG): A retrospective study of 69 patients. Am J Surg Pathol 2016;40:1526-37.
Yih WY, Kratochvil FJ, Stewart JC. Intraoral minor salivary gland neoplasms: Review of 213 cases. J Oral Maxillofac Surg 2005;63:805-10.
Simpson RH, Pereira EM, Ribeiro AC, Abdulkadir A, Reis-Filho JS. Polymorphous low-grade adenocarcinoma of the salivary glands with transformation to high-grade carcinoma. Histopathology 2002;41:250-9.
Nagao T, Gaffey TA, Kay PA, Minato H, Serizawa H, Lewis JE. Polymorphous low-grade adenocarcinoma of the major salivary glands: Report of three cases in an unusual location. Histopathology 2004;44:164-71.
Gnepp DR, Chen JC, Warren C. Polymorphous low-grade adenocarcinoma of minor salivary gland. An immunohistochemical and clinicopathologic study. Am J Surg Pathol 1988;12:461-8.
Edwards PC, Bhuiya T, Kelsch RD. Assessment of p63 expression in the salivary gland neoplasms adenoid cystic carcinoma, polymorphous low-grade adenocarcinoma, and basal cell and canalicular adenomas. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;97:613-9.
Surya V, Tupkari JV, Joy T, Verma P. Histopathological spectrum of polymorphous low-grade adenocarcinoma. J Oral Maxillofac Pathol 2015;19:266.
] [Full text]
Potluri A, Prasad J, Levine S, Bastaki J. Polymorphous low-grade adenocarcinoma: A case report. Dentomaxillofac Radiol 2013;42:14804843.
Weinreb I, Zhang L, Tirunagari LM, Sung YS, Chen CL, Perez-Ordonez B, et al.
Novel PRKD gene rearrangements and variant fusions in cribriform adenocarcinoma of salivary gland origin. Genes Chromosomes Cancer 2014;53:845-56.
Gibbons D, Saboorian MH, Vuitch F, Gokaslan ST, Ashfaq R. Fine-needle aspiration findings in patients with polymorphous low grade adenocarcinoma of the salivary glands. Cancer 1999;87:31-6.
[Figure 1], [Figure 2]