TY - JOUR ID - TI - Immunohistochemical Expression of Actin and S100 in Pleomorphic Adenoma and Mucoepidermoid Carcinoma AU - Ahlam H. Majeed. AU - Farah S. Rasheed PY - 2011 VL - 23 IS - 2 SP - 51 EP - 55 JO - Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد SN - 18171869 23115270 AB - ABSTRACT
Background: Tumors of the salivary glands constitute an important area in the field of oral and maxillofacial
pathology. These tumors have a special status in human neoplasia and probably the most complex histopathologic
features of the body organs and being heterogeneous. Pleomorphic adenoma (PA) is the most common benign;
and mucoepidermoid carcinoma(MEC) is the most common malignant salivary gland tumors. Many investigations
have showed that myoepithelial cells play a major role in the histogenesis of PA and may be important in many
MECs. The aims of the study are to determine the presence and distribution of myoepithelial cell related
immunomarkers Actin and S100 in PA and MEC and to explore the histogenesis of these tumors in relation to the
above mentioned markers.
Materials and methods: Seventeen formalin fixed paraffin embedded tissue blocks of PA, and other fifteen tissue
blocks of MEC were included in the study. Diagnostic confirmation was performed through examination of
hematoxylin and eosin sections. Both tumors were immunohistochemically analyzed for the presence of actin and
S100 protein.
Results: There was a positive immunoreactivity for the expression of actin in PA (100%) with different score values,
while for MEC, actin was negatively expressed in all of the cases (except in one case). There was a highly statistical
significant difference in the actin immunoexpression between the two tumors (p=0.000).
There was a positive immunoreactivity for S100 protein expression in all of the cases of PA and MEC (100%) with
different score values; however, there was no statistically significant difference in the S100 immunoexpression
between them (p=0.545).
Conclusion: The myoepithelial cells are associated with the histogenesis of salivary PA, and the negative expression
of actin in squamous, intermediate and mucous cells of MEC can be explained by the non-involvement of the
myoepithelial cells in the histogenesis of this tumor.
Key words: Pleomorphic Adenoma, Mucoepidermoid Carcinoma, Actin, S100. (J Bagh Coll Dentistry 2011;23(51-55).

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