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Neural adhesion molecule (N-CAM) in pleomorphic adenoma and carcinoma ex-pleomorphic adenoma

Abstract:

Background: The neural cell adhesion molecule (N-CAM) has been implicated in the behaviour of the adenoid cystic carcinoma. In vitro, it was demonstrated that N-CAM inhibits cell invasion. The aim of this study was to search for N-CAM in the most common salivary gland tumour that has a malignant counterpart. Methods: We investigated the presence of N-CAM in pleomorphic adenoma and its malignant counterpart, the carcinoma ex-pleomorphic adenoma, using the immunohistochemistry technique. Results: Neural cell adhesion molecule was expressed in all cases of pleomorphic adenoma, strongly labelling the luminal cells of the double-layered ductform structures. This expression was weaker in neoplastic myoepithelial cells and progressively diminished at a distance from the luminal cells. In carcinoma, expleomorphic adenoma N-CAM was either totally absent or faintly present at the apical pole of the few luminal cells. Conclusions: As a result of the peculiar distribution of N-CAM in pleomorphic adenoma, we speculated that N-CAM behaves as a tumour-suppressor molecule, which is expressed in the benign neoplasm and which is down-regulated after malignancy, when the tumour assumes an invasive behaviour.