Canalicular adenoma of the upper lip: an electron microscopic study

Canalicular adenoma is composed of a row of tall columnar cells adjacent to canalicular lumina and a row of conical cells adjacent to connective tissue stroma. It differs from basal cell adenoma, of the parotid by the lack of well developed desmosomes associated with bundles of tonofilaments; by the presence of moderate numbers of cellorganelles; by a single, inconspicuous basal lamina instead of multi-layering; and by the presence of mucoid material in the stroma. Results suggest that this type of tumor should be considered a specific benign entity of the salivary glands. Cytologic features also suggest that it originates in excretory duct cells of minor salivary glands.