INVERTED DUCTAL PAPILLOMA OF MINOR SALIVARY-GLAND ORIGIN - MORPHOLOGICAL ASPECTS AND CYTOKERATIN EXPRESSION

Ultrastructural features and cytokeratin expression of inverted ductal papillomas of minor salivary gland origin were studied. Under the ele ctron microscope, an increased number of desmosomes and mucus-like gra nules in some cells were the most striking features. Immunohistochemic al study revealed that tumor cells displayed strongly positive reactio ns with cytokeratins 13 and 14, and less strong reactions with cytoker atins 7, 8, 18 and 5D3. These results support the hypothesis that an i nverted ductal papilloma can be derived from the proximal portion of a salivary gland excretory duct.