It has been clarified that myoepithelial cells contain S-100 protein which is known to
be a marker protein of neural tissue. To evaluate the participation of myoepithelial cells
in the histogenesis of the salivary gland tumors, normal salivary glands and various
salivary gland tumors were stained by immune-peroxidase method. PAP kits (DAKO
Co, USA) for the S-100 protein and the Cytokeratin were used and the following results
were obtained.
Acinic cells of the normal salivary gland were negative for both cytokeratin and
S-100 protein. The intercalated duct cells were weakly positive for cytokeratin and
S-100 protein. The normal myoepithelial cells scattered aloud the acini and the
intercalated ducts were positive only for S-100 protein. In contrast, the Striated duct
were positive only for cytokeratin. In plemorphic adenoma, the S-100 protein positive
cells were found in solid sheets of tumor cells, in chondromyxoid areas and in areas of
spindle-cell stroma as well as in the outer layer of the tubular structures. Only the
inner lining of the tubules were positive for cytokeratin. In basal cell adenoma, the
stromal spindle cells were strongly positive for S-100 protein and the epithelial cells
weakly positive. When tubules were present within the epithelial sheets, the inner most
lining cells were positive for cytokeratin. The peripheral Palisaded tumor cells were
negative for both substances. By immunostaining of the adenoid cystic carcinoma, S-100
protein containing cells were found focally scattered independently on the variety of
histologies. The lining cells of true cystic structure were positive for cytokeratin.
Immunostaining of the mucoepidermoid carcinoma demostrated that the squamous cells
and the tubular epithelial cells contained cytokeratin, whereas only a few intermediate
cells were positive for S-100 protein. In Warthin's tumor there were no S-100 protein
positive cells, although basally located epithelial cells of the papillae were positive for
cytokeratin. These findings suggest that salivary gland tumors other than the Warthin's
tumor arise from myoepithelial cells or reserve cells having dual potentiality
differentating into myoepithelial and intercalcated duct cells.
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