The stem cell marker BMI-1 is sensitive in identifying early lesions of carcinoma ex-pleomorphic adenoma

• Grant number: 15/16060-8
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: September 01, 2015
• End date: February 29, 2016
• Field of knowledge: Health Sciences - Dentistry
• Principal Investigator: Fabio Daumas Nunes
• Grantee: Fabio Daumas Nunes
• Host Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

In the present study, we evaluated and described the sensitivity of the stem cell marker B cell-specific moloney murine leukemia virus integration site 1 (Bmi-1) in identifying early lesions of carcinoma ex pleomorphic adenoma. While invasive carcinomas ex pleomorphic adenomas are tumors with a prominent and easily recognizable malignant component, the identification of early carcinomatous changes in pleomorphic adenoma remains a diagnostic challenge due to the lack of objective morphological criteria. The immunohistochemical expression of Bmi-1 was assessed in both adenomatous and carcinomatous components of nine carcinoma ex pleomorphic adenoma cases at an early phase of histological progression (6 intracapsular and 3 minimally invasive) grouped according to the cellular differentiation as luminal (7 cases) or myoepithelial (2 cases). A selective nuclear expression of Bmi-1 was found exclusively in the malignant component of 8 cases (6 luminal-type and 2 myoepithelial-type), including intraductal carcinoma areas, except for one case in which scarce cells of the remnant pleomorphic adenoma were positive. Thus, Bmi-1 is expressed from the earliest morphologically detectable stages of pleomorphic adenoma malignant transformation. When faced with atypical features in pleomorphic adenoma, evaluation of Bmi-1 expression can provide more objective criteria for identification and diagnosis of early lesions of carcinoma ex-pleomorphic adenoma. This is applied to carcinomas with luminal or myoepithelial differentiation. (AU)