The Relationship Between Schwann's Cell Differentiation And Neural Invasion In Salivary Adenoid Cystic Carcinoma And Its Clinical Significances

Adenoid cystic carcinoma (ACC) is the second commonest malignant neoplasm in salivary glands. It has a known propensity for neural invasion, which will lead to frequent recurrences and metastasis. This neurotropism has brought great difficulties to the surgeons. So a lot of scientists were interested in it. Some scientists has found that the neurotropism in desmoplastic melanomas may reflect Schwannian differentiation.Objective: To investigate whether there is Schwann's cell differentiation in adenoid cystic carcinoma, and whether there is any relationship between the Schwann's cell differentiation and neurotropism in ACC. To identify the cell types which the Schwann's cell differentiation take place in. Methods:1. 20 cases of adenoid cystic carcinoma and 18 cases of mucoepidermoid carcinoma had been immunohistochemical stained with antibodies to S100 protein and glial fibrillary acidic protein (GFAP). They are both Schwann's cell markers.2. 20 cases of adenoid cystic carcinoma ,3 cases of mucoepidermoid carcinoma and 2 cases of acinic cell carcinoma had been immunolabled with antibodies to myelin basic protein(MBP),which is also a new kind of Schwann's cell marker.3. Expression of S100, GFAP and muscle actin (MA) in adenoid cystic carcinoma were examined by immunoelectron microscope.4. Double fluorescence immunostain of S100 and MA was used in adenoid cystic carcinoma. The results of double fluorescence immunostain were studied in laser scanning confocal microscope.5. Double fluorescence immunostain of MBP and MA was used in adenoid cystic carcinoma. The results were studied in laser scanning confocal microscope.Results:l.The capability of adenoid cystic carcinoma on neural invasion is more higher than mucoepidermoid carcinoma, S100 and GFAP expressed in most of adenoid cystic carcinoma, but in none of mucoepidermoid carcinoma, there were significant differences(P<0.01).2. Moderate intensity staining for MBP was present in 6 of 20 cases of adenoid cystic carcinoma. But there were no positive staining for MBP in either mucoepidermoid carcinoma or acinic cell carcinoma.3. The distributions and ultrastructures of the S100 postitive cells and MA positive cells are the same. These ultrastructures also meet the characteristics of myoepithelial cells.4.MBP, S100 and MA expressed in the same ACC cells. S100 expressed in both nuclei and cytoplasms of ACC cells while MBP and MA expressed in cytoplasms. Conclusions:1. The Schwann's cell differentiation does occur in salivary adenoid cystic carcinoma. There is strong correlation between Schwann's cell differentiation and neurotropism in adenoid cystic carcinoma. 2. The schwann's cell differentiation occur in the neoplastic myoepithelial cell of the adenoid cystic carcinomas. The Schwann's cell differentiation of modified myoepithelial cell may be the histologic base of neural invasion in adenoid cystic carcinoma.