CANALICULAR ADENOMA - REPORT OF 5 CASES WITH ULTRASTRUCTURAL OBSERVATIONS

Canalicular adenomas from five patients were examined by light and ele ctron microscopy. All patients were over 50 years of age; 4 of the les ions were from the upper lip, 4 were cystic, 2 showed capsular invasio n and 1 was multifocal. Histopathologically there were epithelial duct -like or canalicular structures cut at various angles and epithelial i slands surrounded by hyalinized and mucinous connective tissue that co ntained little collagen. Ultrastructurally the epithelial islands cont ained many small lumina and connective tissue islands. The characteris tic epithelial cell was columnar or cuboidal, extended from the lumina to the connective tissue, had almost straight lateral cell boundaries with desmosomes that predominated near the lumina, and possessed gap junctions and a small number of tight junctions. Their main cytoplasmi c constituents were ribosomes, mitochondria, rough-surfaced endoplasmi c reticulum and microfilaments. These findings show that canalicular a denomas are truly monomorphic and support the concept that they are de rived from the cells of excretory ducts.