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| REVIEW ARTICLE |
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| Year : 2012 | Volume
: 14
| Issue : 1 | Page : 6-10 |
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Epithelial-Myoepithelial carcinoma of the parotid: A rare and difficult malignant tumor to diagnose clinically and radiologicaly
Bandar Al-Qahtani1, Manal Bin-Manie2, Ali Al-Muntashiri3, Osman Ahmed4
1 Consultant, Department of Otolaryngology, King Saud Medical City, Riyadh, Saudi Arabia
2 Resident, Department of Otolaryngology, King Abdulaziz University Hospital, Riyadh, Saudi Arabia
3 Senior registrar Department of Radiology, King Saud Medical City, Riyadh, Saudi Arabia
4 Consultant Department of King Saud Madical City, Riyadh, Saudi Arabia
| Date of Web Publication | 3-Jan-2020 |
Correspondence Address:
Bandar Al-Qahtani
Department of Otolaryngology, King Saud Medical City, Riyadh
Saudi Arabia
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/1319-8491.274774
Epithelial myoepithelial carcinoma (EMC) of the parotid gland is difficult to differentiate from pleomorphic adenoma. EMC is a rare entity and there is not much information about this in literature. We review here the diagnosis, clinical behavior, and treatment of EMC .and in the same time , we recmmend to have early surgical excision if there is nodal metastasis on CAT scan and not to depend on FNAC only if it shows pleomorphic adenoma.
Keywords: parotid gland, malignant tumor, epithelial-myoepithelial carcinoma, salivary gland neoplasm
How to cite this article:
Al-Qahtani B, Bin-Manie M, Al-Muntashiri A, Ahmed O. Epithelial-Myoepithelial carcinoma of the parotid: A rare and difficult malignant tumor to diagnose clinically and radiologicaly. Saudi J Otorhinolaryngol Head Neck Surg 2012;14:6-10 |
How to cite this URL:
Al-Qahtani B, Bin-Manie M, Al-Muntashiri A, Ahmed O. Epithelial-Myoepithelial carcinoma of the parotid: A rare and difficult malignant tumor to diagnose clinically and radiologicaly. Saudi J Otorhinolaryngol Head Neck Surg [serial online] 2012 [cited 2023 Mar 27];14:6-10. Available from: https://www.sjohns.org/text.asp?2012/14/1/6/274774 |
| Introduction | |  |
Epithelial myoepithelial carcinoma is uncommon, accounting for about 1 % of all malignant salivary gland tumors and affecting primarily the parotid gland, Maurer et al [1]. In rare cases it is found in extra oral locations including the nasal cavity, [2], paranasal sinus, lacrimal gland, [3], larynx, [4], trachea, [5], bronchus, [6], breast and external auditory canal. EMC is a low grade malignancy, however, recurrences and metastases to peri-parotid and cervical lymph nodes, as well as to distant sites, have been noted [8].Synchronous bilateral epithelial-myoepithelial carcinoma of the parotid gland have been reported by van Tongeren et al [9]. EMC of the salivary gland was first described in 1972 by Donath et al [10] .It was recognized as a distinct pathologic entity when in 1991 EMC was included in the World Health Organization classification. Imaging for diagnosis and follow up of parotid tumors can be performed using contrast enhanced CT or MRI. Because of their superficial location, parotid tumors are also amenable to assessment by ultrasound (US). US is considered the first-line technique in the radiological study of the parotid lesions. It is easy, quick, repeatable, and a non-invasive procedure. Imaging allows determination of the overall extent of even large tumors and their relationship to adjacent vessels for tumor staging, assessment of resectibility, and planning of extent of neck dissection. A giant EMC measuring around 20 x 20 cm was reported by Maurer et al [1][Figure 1],[Figure 2],[Figure 3]. For diagnosis, FNAB is the baseline investigative tool in the assessment of patients with salivary gland swellings and a method for distinguishing neoplastic from non neoplastic lesions. It has an accuracy of 92%. Pleomorphic and monomorphic adenomas , adenoid cystic carcinomas, and EMCs may be difficult to accurately differentiate by FNAB because needle aspirations from these neoplasms may present with variable amounts of similar appearing components including epithelial aggregates, myoepithelial cells, and extracellular material. FNAB can be consistent with pleomorphic adenoma preoperatively. | Figure 1: Appearance of EMC on axial CT scan shows well defined, heterogeneous enhancing, soft tissue mass within the superficial lobe of the parotid gland with a small deeper extension into the deep portion (red arrow). The tumor Infiltrate the subcutaneous fat with dermal thickening (white arrow). Notice the normal right parotid gland
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 | Figure 2: axial CT scan through the lower part of EMC showswell defined, heterogeneous enhancing, soft tissue mass within the superficial lobe of parotid gland. The tumor Infiltrate the subcutaneous fat with dermal thickening (white arrow). Notice the normal right parotid gland
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 | Figure 3: metastasis of EMC ON axial CT scan with contrast show the jugulodigastric lymph node (white arrow)
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Pathologic features
FNAB is a baseline investigative tool in the assessment of patients with salivary gland swellings and method of distinguishing neoplastic from non neoplastic lesions with 92% accuracy [12]. Pleomorphic and monomorphic adenomas , adenoid cystic carcinomas, and EMCs may be difficult to accurately differentiate by FNAB because needle aspirations from these neoplasms may present with variable amounts of similar appearing components including epithelial aggregates, myoepithelial cells, and extracellular material [13]. FNAB can be consistent with pleomorphic adenoma preoperatively .Grossly and microscopically ,there is a proliferation of ductular structures in the gland. The ducts may be seen in cross section or longitudinally, and they may be densely packed together or separated by abundant dense hyaline material. The inner cells of these ductules constitute the epithelial component of EMEC. These mildly to moderately pleomorphic cells have irregular ovoid shapes, may overlap and have prominent nucleoli and fine chromatin. Mitotic figures are not common. The outer cell layer that surrounds the ductules is the clear cell myoepithelial component of EMEC. The nuclei are smaller than those of the epithelial cells, with a definitely condensed and triangular appearance [4] [Figure 4],[Figure 5],[Figure 6]. | Figure 4: intra operative picture of the parotid EMC ,note pseudopodes similar to pleomorphic adenoma grossly
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Radiologic features
Imaging for diagnosis and follow up of parotid tumors can be performed using contrast enhanced CT or MRI. Because of their superficial location, parotid tumors are also amenable to assessment by ultrasound and considered the first-line technique in the radiological study of the parotid lesions. it is easy , quick, repeatable and non-invasive procedure [14]. Imaging allow determination of the overall extent of even large tumors and their relationship to adjacent vessels for tumor staging, assessment of resectibility, and planning of extent of neck dissection. A gaint EMC measuring around 20x20 cm was reported by Maurer et al [1].
| Discussion | | |
The most common benign parotid tumors are pleomorphic adenomas, myoepitheliomas, basal cell adenomas, oncocytomas, and cystadenolymphomas (Warthin tumors). The malignant tumors include mucoepidermoid and acinic cell carcinomas as the most common entities and the rare EMCs [1].
FNAB is a baseline investigative tool in the assessment of patients with salivary gland swellings and method of distinguishing neoplastic from non neoplastic lesions with 92% accuracy [12]. Pleomorphic and monomorphic adenomas , adenoid cystic carcinomas, and EMCs may be difficult to accurately differentiate by FNAB because needle aspirations from these neoplasms may present with variable amounts of similar appearing components including epithelial aggregates, myoepithelial cells, and extracellular material [13]. FNAB can be consistent with pleomorphic adenoma preoperatively.
Imaging for diagnosis and follow up of parotid tumors can be performed using contrast enhanced CT or MRI. Because of their superficial location, parotid tumors are also amenable to assessment by ultrasound and considered the first-line technique in the radiological study of the parotid lesions. it is easy , quick, repeatable and non-invasive procedure [14]. Imaging allow determination of the overall extent of even large tumors and their relationship to adjacent vessels for tumor staging, assessment of resectibility, and planning of extent of neck dissection. A gaint EMC measuring around 20*20 cm was reported by Maurer et al [1] . Treatment of EMC is complete surgical resection. Long-term follow up is mandatory to detect early recurrence [13] .
Recurrences are seen in slightly over 30% of patients and nodal metastases in approximately 18% [7] . Local aggressive behavior with direct intracranial invasion was reported by Amin et al ( 8) . Wilkinson et al report a case of EMC with lung metastasis who was initially diagnose as pleomorphic adenoma [15] .
| Conclusion | | |
The most common benign parotid tumors are pleomorphic adenomas , myoepitheliomas ,basal cell adenomas , oncocytomas , and cystadenolymphomas (Warthin tumors ). The malignant tumors include mucoepidermoid and acinic cell carcinomas as the most common entities and the rare EMCs 1 . Treatment of EMC is still surgical resection with Long-term follow up is mandatory to detect early recurrence , So we advice to have early surgical excision if there is nodal metastasis on CAT scan and not to depend on FNAC only.
| References | | |
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| 8. | Amin K S, McGuff H. S, Cashman S W, et al Recurrent epithelial-myoepithelial carcinoma of the parotid with direct intracranial extension. Otolaryngol Head Neck Surg. 2002;126:83-4. |
| 9. | Van Tongeren J, Creytens D H K V, Meulemans E V, et al Synchronous epithelial-myoepithelial carcinoma of the parotid gland: case report and review of the literature. Eur Arch Otorhinolaryngol. 2009;266:1495-500. |
| 10. | Donath K, Siefert G, Schmitz R, Zur diagnose und ultrastruktur des tubulaeren speichelgangkarzinoms epithelial-myoepitheliales shaltstueckkarzinom. Virchows Arch A. 1972;356:10-31. |
| 11. | Seifert G, Sobin LH, Histologic typing of salivary gland tumors, Inl:world health organi zation international histologic classification of tumors, Berlin. Spriger (1991). |
| 12. | Costas A, Castro P, Martin-Granizo R,et al Fine needle aspiration biopsy (FNAB) for lesions of the salivary glands, British. J Oral Maxillofacial Surg. (2000)38:539-542. |
| 13. | Kumagai M, Suzuki H, Matsuura K,et al Epithelial-myoepithelial carcinoma of the parotid gland. Auris Nasus Larynx. 2003; 30:201-203. |
| 14. | Gritzmann N, Rettenbacher T, Hollerweger A, et al Sonography of the salivary glands. Eur Radiol. 2003;13:964-975. |
| 15. | Wilkinson L, Cook P, Bioxham C, Malignant myoepithelial carcinoma of the parotid gland metastasizing to the lungs. Diagn Histopath. 2008;614-617. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
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