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Year : 2015  |  Volume : 58  |  Issue : 2  |  Page : 201-203
Oncocytic variant of mucoepidermoid carcinoma: A diagnostic challenge for the pathologist

1 Department of Pathologic Anatomy, AORN A Cardarelli, Naples, Italy
2 Department of Pathologic Anatomy, A. U. O. San Giovanni di Dio e Ruggi d'Aragona, Salerno, Italy
3 Department of Pathologic Anatomy, ASL Salerno 1, Hospital "Tortora", Pagani (SA), Italy
4 Department of Pathologic Anatomy, AO Sant'Anna e San Sebastiano, Caserta, Italy

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Date of Web Publication17-Apr-2015


Oncocytic mucoepidermoid carcinoma of the salivary gland is rare. We report a 48-year-old man who presented with a slowly growing right parotid mass. A preoperative fine needle aspiration showed exclusively oncocytic cells and cellular debris. A first diagnosis of Warthin tumor or myoepithelioma was made. The patient underwent a superficial parotidectomy, and her postoperative course was uneventful. Histologically, the tumor was composed of solid nests and cystic gland containing clear mucoid material, lined predominantly with oncocytes and few mucous goblet cells. A final diagnosis of oncocytic variant of mucoepidermoid low-grade carcinoma was made. The recognition of this variant is important, because may be easy confused with most frequent benign tumor with oncocytic cells; in this case a complete surgical excision and long-term clinical follow-up are an adequate management.

Keywords: Mucoepidermoid carcinoma, oncocytic variant, parotid gland

How to cite this article:
D'Antonio A, Boscaino A, Caleo A, Addesso M, Orabona P. Oncocytic variant of mucoepidermoid carcinoma: A diagnostic challenge for the pathologist. Indian J Pathol Microbiol 2015;58:201-3

How to cite this URL:
D'Antonio A, Boscaino A, Caleo A, Addesso M, Orabona P. Oncocytic variant of mucoepidermoid carcinoma: A diagnostic challenge for the pathologist. Indian J Pathol Microbiol [serial online] 2015 [cited 2020 Jul 9];58:201-3. Available from: http://www.ijpmonline.org/text.asp?2015/58/2/201/155315

   Introduction Top

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy and most occurred in the parotid. [1] The oncocytic variant of MEC (OMEC) composed mainly of oncocytic cells has been rarely reported. [2],[3],[4],[5],[6],[7] We described a case of OMEC in man with a preoperative diagnosis of Warthin tumor.

Our case demonstrated that this diagnosis can be very difficult due to overlapping cytomorphology with numerous benign lesions containing exclusively or not oncocytic cells.

   Case Report Top

A 48-year-old man was admitted our hospital because of a right parotid painless mass.

Ultrasonography of the right parotid region showed a prevalently hyperechoic oval mass in the parotid gland. The lesion was not homogeneous, relatively circumscribed, but not capsulated.

A preoperative fine needle aspiration (FNA) was performed; low-power magnification of a Diff-Quik stained FNA specimen showed oncocytic fragments or pseudopapillary aggregates present in a background of lymphocytes and cellular debris [Figure 1]. A first diagnosis on FNA was "salivary gland neoplasm favor Warthin tumor."
Figure 1: Fine needle aspiration specimen showed oncocytic fragments or pseudopapillary aggregates with a background of lymphocytes and cellular debris (Diff-Quik ×40)

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A superficial parotidectomy was performed with preservation of the facial nerve. After 2 years the patient is well with no evidence of tumor recurrence.

The lesion was partially circumscribed but not capsulated, gray-yellowish with microcystic cut surface, and its largest diameter measured 3.2 cm × 2.2 cm.

The histological features consisted of a multiple not encapsulated nodules composed predominantly of oncocytes [Figure 2]; high-power magnification showed some cystic glands contained varying amounts of mucin and lined by oncocytes with rare mucous cells, pseudo-goblet cells and clear cells [Figure 3]. Secretory material stains positive for periodic acid-Schiff with and without diastase and for alcian blue. A minimal number of squamous cells were also present. Intense CK8/18 and plurifocal p63 positivity were found in the oncocytic cells while Ki-67-labeled cells were 5%.
Figure 2: Parotid tumor was composed predominantly of oncocytes (H and E, ×10)

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Figure 3: At high-power magnification the cystic glands contained amounts of mucin and was lined by oncocytes with rare mucous cells (H and E, ×40)

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Based on the criteria described by Weinreb et al., [7] a diagnosis of OMEC was made.

Subsequently we have reviewed FNA specimen and after a careful examination at high-power magnification, an aggregate of histiocyte-like (clear) cells with vacuolated cytoplasm were demonstrated. In this case, a diagnosis suggestive of OMEC should be made also on FNA material.

   Discussion Top

Mucoepidermoid carcinoma is the most common malignant salivary gland tumor and accounts for 5-10% of all salivary gland neoplasms. [1] This tumor is usually composed of three type of cells: Epidermoid (squamoid) cells, intermediate cells, and mucous cells. [1] The majority of MEC occur in the parotid gland resulting in accessibility to biopsy by FNA; however, the diagnosis of MEC can be difficult due to combination of the three cellular elements in varying proportions and to overlapping cytomorphology with benign lesions. [8]

Rarely MEC is composed predominantly of oncocytc cells resulting in an OMEC. [2],[3],[4],[5],[6],[7] The presence of OMEC can be the cause of diagnostic challenges because extensive oncocytic change are present in numerous salivary tumors specially of a benign nature. [2],[3],[4],[5],[6],[7] Specific oncocytic lesions of salivary glands are oncocytoma, nodular oncocytic hyperplasia, and oncocytic carcinoma, but oncocytic cells are present also in myoepithelioma, Warthin tumor, and some pleomorphic adenoma. The clinical course and the therapeutical management of these tumors are different. Instead an accurate diagnosis of all oncocytic lesions is critical for a correct treatment. To time, a complete surgical excision and long-term clinical follow-up are adequate management of all case of MEC.

The MEC are graded on the basis of prevalence of mucous cells (low grade, >50% of mucous elements, intermediate grade, 10-50% of mucous cells and high grade <10% of mucous cells) and histopathologic grading represents the main prognostic indicator. [1],[9],[10] Previous reported cases suggested that the majority of OMEC presented to time of diagnosis as a low-grade neoplasms and showed a favorable prognosis. [2],[3],[4],[5],[6],[7] Also in the present case, the patient is free of disease after 2 years to the diagnosis, although a superficial paroidectomy was performed.

A preoperative FNA diagnosis of MEC in presence of extensive oncocytic change may be very difficult and lead to erroneous diagnosis of benign tumor as our case. Instead, an adequate sampling and the identification of the almost one of the many cytologic features described (extracellular mucin, mucous cells, and intermediate cells) in association with oncocytic cells should raise the suspicion of MEC also in FNA specimens.

To avoid false-negative diagnoses, the cytopathologist should be aware that a variant of MEC composed mainly of oncocytic cells may occur in salivary gland.

Fine needle aspiration biopsy diagnosis of OMEC also allows to rule out other primary salivary gland tumors that may be clinically and instrumentally indistinguishable and thereby permits an appropriate surgical procedure to ensue.

   References Top

Goode RK, El-Naggar AK. Mucoepidermoid carcinoma. In: Barnes L, Eveson J, Reichart P, Sidransky D, editors. World Organization Classification of Tumors. Pathology and Genetics. Head and Neck Tumours. Lyon: IARC Press; 2005. p. 219-20.  Back to cited text no. 1
Jing H, Meng Q, Tai Y. Oncocytic mucoepidermoid carcinoma with prominent tumour-associated lymphoid proliferation of the submandibular gland. Oral Oncol 2012;48:e7-8.  Back to cited text no. 2
Brannon RB, Willard CC. Oncocytic mucoepidermoid carcinoma of parotid gland origin. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;96:727-33.  Back to cited text no. 3
Wade TV, Livolsi VA, Montone KT, Baloch ZW. A cytohistologic correlation of mucoepidermoid carcinoma: Emphasizing the rare oncocytic variant. Patholog Res Int 2011;2011:135796.  Back to cited text no. 4
Corcione L, Giordano G, Gnetti L, Multinu A, Ferrari S. Oncocytic mucoepidermoid carcinoma of a submandibular gland: A case report and review of the literature. Int J Oral Maxillofac Surg 2007;36:560-3.  Back to cited text no. 5
Deveci MS, Deveci G, Günhan O, Finci R. Oncocytic mucoepidermoid carcinoma of the parotid gland: Report of a case with DNA ploidy analysis and review of the literature. Pathol Int 2000;50:905-9.  Back to cited text no. 6
Weinreb I, Seethala RR, Perez-Ordoñez B, Chetty R, Hoschar AP, Hunt JL. Oncocytic mucoepidermoid carcinoma: Clinicopathologic description in a series of 12 cases. Am J Surg Pathol 2009;33:409-16.  Back to cited text no. 7
Cohen MB, Fisher PE, Holly EA, Ljung BM, Löwhagen T, Bottles K. Fine needle aspiration biopsy diagnosis of mucoepidermoid carcinoma. Statistical analysis. Acta Cytol 1990;34:43-9.  Back to cited text no. 8
Brandwein MS, Ivanov K, Wallace DI, Hille JJ, Wang B, Fahmy A, et al. Mucoepidermoid carcinoma: A clinicopathologic study of 80 patients with special reference to histological grading. Am J Surg Pathol 2001;25:835-45.  Back to cited text no. 9
Evans HL. Mucoepidermoid carcinoma of salivary glands: A study of 69 cases with special attention to histologic grading. Am J Clin Pathol 1984;81:696-701.  Back to cited text no. 10

Correspondence Address:
Dr. Antonio D'Antonio
Department of Pathologic Anatomy, A. U. O. San Giovanni di Dio e Ruggi d'Aragona, Via San Leonardo, 2, 84124 Salerno
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.155315

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  [Figure 1], [Figure 2], [Figure 3]

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