Ultrastructure of granular cell ameloblastoma

Abstract

To our knowledge, this is the first description of the ultrastructure of the granular cell ameloblastoma, an odontogenic tumor. The granular cells of this tumor are shown to be epithelial in origin. The organelles resulting in their cytoplasmic eosinophilia, as seen in the light microscope, are mainly pleomorphic, osmiophilic lysosome-like granules. A comparison with granular cell myoblastoma shows a striking morphological similarity between the cytoplasmic granules of these two lesions. We conclude that the granular cell ameloblastoma and the granular cell myoblastoma, probably along with the granular cell ameloblastic fibroma and the congenital epulis, constitute a group of lesions in which the lysosomes are the common denominator as the expression of their cytoplasmic eosinophilia.