Clinicopathological and immunohistological study of salivary gland tumors

Abstract

A total of 126 cases of salivary gland tumors were studied from clinicopathological view point. A particular attention was paid to the reason for the recurrence in pleomorphic adenoma and to the prognosis of adenoid cystic carcinoma. Immunohistological reaction for many markers including lysozyme, lactoferrin, Al-p, keratin, S-100, actin, vimentin, CEA, etc., using PAP method was performed to investigate the origin of tumor cells and to obtain an indicator for malignancy.In recurrent cases with plemorphic adenoma, myxochondromatous pattern was more frequently observed than other patterns, even if no correlation to the numbers of atypical cells and of mitotic figures. A relation between the recurrence and proliferation of tumor cells was not speculated because of an equal frequency of Ki-67 positive cells irrespectively histological subtypes of pleomorphic adenoma. In adenoid cystic carcinoma, the cases with solid pattern, occupying only a part of tumor, had poor prognosis. It was presumably considered that the solid pattern in adenoid cystic carcinoma might reflect high grade malignancy.Immunohistologically, salivary gland tumors, benign or malignant, are composed of lines of ductal epithelial cells. In malignant tumors, however, it was rather difficult to determine the cell origin because of a poor immunohistological reaction. A localization of CEA was different in benign tumors from malignant tumors, showing that it was positive for luminar border of ductal epithelium in former and positive for cytoplasma of tumor cells in latter, particalurly in mucoepidermoid carcinoma and acinic cell carcinoma. CEA might be useful for differential diagnosis in certain histologic types. Ki-67 is known as antigen positive for nuclei of proliferating cells, but there has been no report on salivary gland tumors. In this study, Ki-67 positive cells in malignant tumors were higher than those of normal gland benign tumors. A high frequency of Ki-67 positive cells in salivary gland tumors may give a clue for malignancy.