Kouji Tsukitani

Myoepitheliomas and Myoepithelial Adenomas of Salivary Gland Origin: Immunohistochemical Evaluation of Filament Proteins, S-100 α and β, Glial Fibrillary Acidic Proteins, Neuron-specific Enolase, and Lactoferrin

Immunohistochemical identification of keratin proteins (TK, KL1 and PKK1), vimentin, myosin, S-100 protein (using polyclonal antiserum) and S-100 alpha and beta subunits, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), lactoferrin, and lysozyme was made in myoepitheliomas, myoepithelial adenomas, and clear cell adenomas of salivary gland origin. Myoepithelioma cells were divided into two types: plasmacytoid cells, which showed great heterogeneity in terms of keratins and S-100 alpha and beta proteins and a lack of GFAP, NSE, lactoferrin, and lysozyme in most the cells, and fibrous and dendritic tumor cells, which displayed variable staining for keratin and S-100 alpha and beta proteins. Myoepithelial adenomas were composed of small-, intermediate-, and large-sized spindle cells that showed irregular positive reactions for keratins and S-100 alpha and beta. Immunohistochemical deposition of S-100 protein was restricted strongly to the dendritic cells present in hyalinous and myxomatous areas. Clear cell adenomas revealed uniformly slight staining of keratins and S-100 proteins, and negative staining or rarely positivity for GFAP, NSE, lactoferrin, and lysozyme. When the immunohistochemical deposition of these proteins was compared between normal glands and myoepithelial tumors, heterogeneity of expression of keratins, S-100 proteins, GFAP, and NSE was notable in the tumors. Progenitor cells of several kinds of myoepithelioma were suggested to be intercalated reserve cells, which are thought to be the same cell that gives rise to pleomorphic adenoma of salivary glands.

Immunohistochemical localization of the α and β subunits of S-100 protein in pleomorphic adenoma of the salivary glands

SummaryThe immunohistochemical expression of the α andβ subunits of S-100 protein in reactive, modified and transformed of myoepithelial cells, salivary pleomorphic was investigated using monoclonal antibodies. With S-100 α, normal salivary glands showed strong staining in serous acinar cells and moderate to slight staining in ductal segments, and with S-100β staining was slight or negative in acinar cells, but strong in nerve fibres. In pleomorphic salivary adenomas, the immunohistochemical distribution of S-100 α andβ proteins indicated great variation in the tumour cells. Some neoplastic cells gave similar staining for both S-100 α andβ, others were strongly positive for S-100 α and stained only slightly for S-100 /gb, or vice versa. Yet other cells were positive for S-100 α and negative for S-100β, or vice versa. Pleomorphic salivary adenomas were classified both by histopathological criteria and by their staining pattern for S-100 α andβ proteins. Great heterogeneity in S-100 α andβ protein expression was found in individual tumour cells of both ductal and myoepithelial origin, and no regular pattern was identified.The cellular origin of salivary pleomorphic adenomas is discussed in terms of S-100 α andβ protein immunohistochemistry. Pleomorphic adenoma cells may be transformed from reserve cells into tumour cells displaying biologic properties of myoepithelial cells, ductal cells, or a mixture of both.

Immunohistochemical distribution of human epidermal growth factor in salivary gland tumours

Immunohistochemical identification of human epidermal growth factor (hEGF) was carried out in a total of 152 cases of salivary gland tumours, consisting 107 pleomorphic adenomas and their variants, 13 adenolymphomas and 32 adenoid cystic carcinomas. A high percentage of pleomorphic adenomas revealed markedly positive hEGF staining of the luminal surface cells of tubuloductal structures and of modified or neoplastic myoepithelial cells. Clear cells of the tumour showed various reactivities from very slight to strong. Eosinophilic epithelial cells of adenolymphoma gave a positive reaction for hEGF in all the cases, whereas most adenoid cystic adenoma lacked hEGF staining; however some cases showed positive staining of the tumour cells. The immunohistochemical detection of hEGF in most salivary gland tumours suggests this factor to be a possible new marker of salivary glands tumours, and to have a biological role in tumour proliferation.