Apoptosis-induced and -suppressed cells in salivary gland adenoid cystic carcinoma: correlation with histological growth patterns.

OBJECTIVE: It is well known that adenoid cystic carcinoma (ACC) arising from salivary glands shows a correlation between prognosis and histological growth patterns. The aim of the study was to evaluate whether three growth patterns of ACC are related to the distributions of apoptosis-induced and -suppressed tumor cells. MATERIALS AND METHODS: We examined 77 cases of ACC including tubular (18 cases), glandular (50) and solid (9) patterns. In order to visualize the apoptotic cells, terminal deoxynucleotidyl transferase (TdT)- mediated dUTP-biotin nick end labeling (TUNEL) and avidin-biotin complex staining using Lewis Y (Le(Y)) antibody were applied to paraffin sections. For detection of the apoptosis-suppressed cells, immunohistochemistry employing bcl-2 antibody was utilized. RESULTS: Apoptosis index (Al) based on the TUNEL-stained specimens were tubular, 7.0; glandular 2.4; solid, 5.1, In tubular type, apoptotic cells were frequently located in the inner tubular layer rather than the outer layer. Solid type had scattered apoptotic cells in the nests. Bcl-2 expression was found in 61% of tubular, 20% of glandular and 22% of solid cases. The localization of bcl-2 protein was noticed in outer tubular cells, and peripheral cells or undifferentiated cells in solid pattern. CONCLUSIONS: The peculiar distribution of apoptotic cells may result from the various proportions and distinctive arrangement of neoplastic ductal cells and neoplastic myoepithelial cells in ACC. Apoptotic cells and bcl-2 positive apoptosis-suppressed cells may participate in the construction of characteristic histological appearances of ACC.