Objective: Objective of this study is to highlight the importance of considering clinical and radiological findings in parotid tumors before operating tumors with high suspicion of malignancy though reported as benign on histopathology. Material and Methods: 20 years old female patient underwent radical parotidectomy for epithelial-myoepithelial carcinoma of the left parotid gland which was diagnosed on FNAC. Contrast CT and contrast MRI also showed a tumor involving left parotid gland with destruction of ramus of mandible and loss of tissue planes medially & laterally. Facial nerve was infiltrated by tumor, thus sacrificed. Post operatively, patient had left facial palsy and was discharged after 7 days without any other sequelae. Postoperative histopathology showed pleomorphic adenoma with positive resection margins medially, superiorly & posteriorly. No further treatment was given in view of the benign nature of the tumor. Results: Patient was kept on monthly follow up and was disease free at one year follow up. Conclusion: Aggressive surgical treatment should be planned for malignant parotid tumors to give a better tumor free survival. Misdiagnosis can occur on FNAC as it can hit only one part of the tumor thus missing a malignant tumor or can interpret pleomorphic adenoma as epithelial-myoepithelial carcinoma.
Pleomorphic adenoma is the most common neoplasm of both the major and minor salivary glands. It is composed of an array of tissue types, of both epithelial and mesenchymal origins, and is regarded as benign in clinical behavior, but has the potential to undergo malignant transformation. Epithelial-myoepithelial carcinoma (EMC) is a rare biphasic tumor of the salivary glands typically arising in the parotid. Fine needle aspiration cytology is widely used in the initial investigation of salivary gland swellings and whilst the cytological features of this tumour have been described they are not well recognized. Epithelial-myoepithelial carcinoma (EMC) is a rare type of malignant tumor, accounting for about 1% of all salivary gland tumors [1,2] and recognizes a typical biphasic pattern: a central ductular structure, often containing eosinophilic material surrounded by clear cells of myoepithelial origin. It was firstly described as a glycogenrich or clear cell adenoma because of the clear cell component. Donath et al. [
A 22 years old woman presented to our institution with a 6 months history of a painless swelling in the region of the left parotid gland. On examination, a 7 cm diameter, firm tumor mass was palpable in the gland. The growth was well demarcated, extending from zygomatic arch to angle of mandible with a smooth external appearance. It had a moderately firm consistency with fixity to neighboring tissues. It was non-tender with no associated facial weakness or cervical lymphadenopathy. The oral cavity was normal on inspection.
Ultrasonography done at another center revealed normal parotid glands with hypoechoic thickening with amorphous calcification seen deep to the gland. Fine needle aspiration done in private hospital showed the presence of round cells with moderate to abundant cytoplasm, which was vacuolated in few cells. Nuclei were round to oval with finely stippled cytoplasm. Some of the cells were binucleate. The cytological interpretation was not specific. Possibility of osteogenic, chondrogenic or reticuloendothelial cell origin was suggested.
Fine needle aspiration cytology done at our institute showed predominant scattered and occasional clusters of malignant cells, the tumor cells were round to oval with eccentrically placed nuclei, prominent nucleoli and moderate to abundant amount of basophilic cytoplasm. Many multinucleated giant cells, atypical mitotic figures were also noticed. Overall features were suggestive of myoepithelial, epithelial carcinoma (
MRI done at our institute-revealed a 7 × 5 × 5 cm lobulated soft tissue mass extending on both sides of left
mandible, heterogeneously hyper-intense on T2 (
Under general anesthesia, 7 × 5 cm hard left parotid mass (
Macroscopically, the tumor was solid and well encapsulated, multilobulated with foci of hemorrhage. There was no capsular breach. Histopathologic examination showed that the encapsulated tumor was having an extensive chondromyxoid background, within which islands and trabeculae of tumor cells were present. Cells had
moderate amount of cytoplasm with peripherally pushed nucleus and fine nuclear chromatin. Numerous mitotic figures were seen with tumor infiltration into the underlying mandible, the medial, posterior and superior resection limits formed by the tumor, the inferior, lateral and anterior resection limits were free. Overall features were those of pleomorphic adenoma (
Postoperative period was uneventful with facial paralysis. There was no evidence of disease at one year follow-up.
To highlight the importance of considering clinical and radiological findings in parotid tumors before operating tumors with high suspicion of malignancy though reported as benign on histopathology.
Approximately 1% of salivary gland tumors are epithelial myoepithelial carcinomas. Although they have predilection for parotid gland they may arise in minor salivary glands and rarely in extra oral sites such as the paranasal sinuses, pharynx, bronchus, palate. It is seen predominantly in elderly women with peak incidence in 7th decade.
Clinical presentation is not specific and is usually that of a long-standing and progressively enlarging painless mass. Facial nerve palsy occurs only rarely [
not encapsulated and may be multinodular. Microscopically on histological examination the tumor is biphasic and characterized, as in this case, by tubules lined by an inner layer of cytokeratin-positive bland cuboidal epithetlial cells surrounded by an outer layer of S100 positive myoepithelial cells.
Characteristic extracellular globules of hyaline basement membrane material are present [7,8]. Typically the tumor nodules have an infiltrative margin and perineural and vascular invasion are present. In keeping with other biphasic tumors the diagnosis maybe difficult histologically and other salivary gland tumors such as pleomorphic adenoma, adenoid cystic carcinoma and also tumors with a predominant clear cell population such as clear cell carcinoma and sebaceous carcinoma should be considered before rendering the diagnosis. Fine needle aspiration cytology is a baseline investigative tool in the assessment of patients with salivary gland swellings. Whilst it is an accurate method of distinguishing neoplastic from non-neoplastic lesions it may not be possible to always accurately predict a specific tumor type due to the overlapping spectrum of cytological appearances found in a wide variety of salivary gland neoplasms. This can result in a differential diagnosis given in the cytology report in those tumors not characteristic of a specific entity. Four cell types are identified in myoepithelial salivary gland neoplasms: namely, plasmacytoid, spindle, epithelioid and clear cell types. Of these, the clear cell type is the least frequently encountered [9,10].
A review of the world literature in 2000 disclosed approximately 75 cases of myoepithelial carcinoma [
There are few reports on the cytological features of EMC [18-23] and in only one of these was the diagnosis considered prior to surgery [
This is an interesting case in which pleomorphic adenoma of the parotid mimicked as carcinoma clinically and radiologically. Though, epithelial-myoepithelial carcinoma is very rare salivary gland tumor, it should not be missed as under treatment may lead to recurrence and can reduce the survival in such patients. Radical surgery followed by radiotherapy remains the treatment of choice for this cancer.