The purpose of this immunohistochemical study was to know the degree and direction of differentiation, the mechanism of mesenchymal appearance, and histogenesis in
pleomorphic adenomas which were obtained from surgical removed specimens. All specimens were fixed in 10% neutral phosphoate buffered
formalin, and embedded in
paraffin. Sections were steined with the
avidin-
biotin peroxidase complex method for
keratin,
vimentin,
desmin and
S-100 protein, the
peroxidase-antiperoxidase method for
lysozyme, and the direct immunoperoxidase method for
IgA and
secretory component. Normal salivary glands were employed as controls. 1. Solid portion of
pleomorphic adenomas were consisted of the focal hypline cells and scattered the duct cell-like cells. The hyaline cells were positive for
vimentin and
S-100 protein, and the duct cell-like cells were positive for
keratin. But one case was found the bundles of spindle-shaped cells which was similar to myoepithelial cells were positive for actin and another case was consisted of the focal duct cell-like cells were observed. 2. In the tubular portion, the duct-like structures were classified into three types. One type was mono-layered structure, another type was double-layered structure and the other type is duct-like structure in the solid portion. Any inner layer of the duct-like structure were positive for
keratin. 3. Double-layered duct-like structures were most common type. Among the double-layered structures, hyaline cells mostly made up the outer layered structures. At times, the spindleshaped cells of the outer layer were found. This structures were similar to intercalated portion of normal salivary glands. In one case, inner and outer layer was consisted of
keratin positive cells, but outer layer was steined for
keratin stronger than inner. This structure was similar to excretory duct of normal salivary glands. 4.
IgA and sc were seen at inner cells and in
luminal accumulation of the duct-like structures. 5. In the myxoid regions, stellate cells or spindle cells were positive for
vimentin,
S-100 protein and partial positive for
desmin. In the chondroid regions, chondrocyte-like cells were positive for
vimentin and
S-100 protein. These results seemed to suggest that
pleomorphic adenomas were composed of duct cell-like cells and hyaline cells. Duct cell-like cells consisted of the duct-like structure in order to transport secretion which was similar to the duct of normal salivary glands.(ABSTRACT TRUNCATED AT 250 WORDS)