 The cells of an EIN lesion are genetically different than normal and malignant tissues, and have a distinctive appearance under the light microscope.EIN cells are already neoplastic, demonstrating a monoclonal growth pattern and clonally distributed mutations.Progression of EIN to carcinoma, effectively a conversion from a benign neoplasm to a malignant neoplasm, is accomplished through acquisition of additional mutations and accompanied by a change in behavior characterized by the ability to invade local tissues and metastasize to regional and distant sites.