Myoepithelioma of minor salivary glands - A diagnostic challenge: Report of three cases with varied histomorphology

Abstract

Myoepitheliomas are rare, benign neoplasms affecting predominantly parotid gland and to a lesser extent minor salivary glands. In this article we have reported three cases with different histomorphological patterns. Two cases are from oral cavity and one from sinonasal tract, a very rare location. We have discussed different histomorphological patterns of myoepitheliomas, which at times possesses a real diagnostic dilemma to a pathologist. Along with its morphology, immunohistochemical profile and clinical behavior are discussed in detail with relevant review of literature.

Myoepithelioma of Parotid: A diagnostic dilemma

“…However other studies show no predilection with regard to gender and age. 1 Myoepitheliomas were considered as a variant of Pleomorphic adenoma in past, but since 1991 it has been considered as a separate clinical entity by WHO. 4 Myoepitheliomas of parotid usually present as encapsulated lesions with no ulceration.…”

“…4 Myoepitheliomas of parotid usually present as encapsulated lesions with no ulceration. 1 Pleomorphic adenoma, basal cell adenoma and myoepithelioma are benign salivary gland tumors with myoepithelial cell participation that appear to lie in a continuum. Histologically, myoepithelioma can be viewed as an extreme form of basal cell adenoma without a ductal component (less than 5-10%) while basal cell adenoma is pleomorphic adenoma mi nus the characteristic stroma.…”

“…To consider a diagnosis of pure myoepithelioma, the epithelial component should be less than 5% -10% and fibromyxoid stroma should be absent. 1 Identification of myoepithelioma is important as WHO classification attributes a more aggressive behaviour to it as compared to Pleomorphic adenoma. 1,4 In some studies possibility of malignancy arising in myoepithelioma is 20% as compared to 5.2% in Pleomorphic adenoma.…”

“…Less than 100 cases have been reported in the literature till 2013. 1 The most common site of occurrence is parotid gland (50%) followed by sublingual gland (33%), submandibular gland (13%) and very rarely in oral cavity (1.5%). 2 The varied histomorphology of these tumours, further confounded by their varied clinical behaviour presents many gray areas which need to be further studied.…”

“…2 The varied histomorphology of these tumours, further confounded by their varied clinical behaviour presents many gray areas which need to be further studied. 1 Although the cytological features are documented in a few case reports, it has rarely been diagnosed preoperatively by fine needle aspiration cytology. …”