The morphological distinction between benign and malignant or in situ and invasive breast lesions can be problematic at times due to considerable interobserver disagreement in the interpretation of difficult breast lesions based on histology alone. The presence of myoepithelial layer characterizes all normal, benign as well as in situ lesions of breast whereas the loss of myoepithelial layer is the hallmark of invasive carcinoma which can be demonstrated by immunohistochemical techniques.

          In  this  study,  we  have  made  an  effort  to  study  the  significance 

of expression  of  SMMHC (Smooth Muscle Myosin Heavy Chain), a myoepithelial marker, in  various  benign  and  malignant  lesions of  breast.