SALIVARY-GLAND MONOMORPHIC ADENOMA - ULTRASTRUCTURAL, IMMUNOPEROXIDASE, AND HISTOGENETIC ASPECTS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 115  (3) , 334-348
Abstract
Monomorphic adenoma of basal cell type is a salivary gland tumor [human] believed to result from a proliferation of a single type of cell. Ultrastructural and immunocytochemical investigations of 6 monomorphic adenomas (5 from parotid and 1 from intraoral minor salivary gland) indicate that there are 2 classes of these lesions, 1 composed of 2 types of tumor cells and the other wholly or predominantly made up of 1 type of cell (isomorphic). In the former group, the organization of the tumor cells closely mimicked that of normal and hyperplastic salivary gland intercalated ducts. Aggregates of tumor cells were arranged as an inner layer of luminal epithelial cells which were surrounded by an outer layer of cells that, in some cases, had ultrastructural and immunohistochemical features indicating myoepithelial cell differentiation. In some adenomas formed by 2 types of tumor cells, basal-lamina-lined extracellular spaces were identified ultrastructurally in relation to modified myoepithelial cells; such spaces had the same fine-structural features as those reported in pleomorphic adenomas and adenoid cystic carcinoma. Predominantly isomorphic adenomas were composed exclusively of luminal epithelial cells. The varied histologic patterns in the numerous subtypes of monomorphic adenoma indicate that there is a central theme of differentiation and organization in this type of neoplasm which recapitulates the ductoacinar unit of normal salivary gland parenchyma.