AIMS: Polymorphous low-grade adenocarcinoma (PLGA) and adenoid cystic carcinoma (ACC) are malignant salivary gland tumours bearing many similar histological patterns. This study was undertaken to show how the presence and distribution of collagen IV and laminin, and their ligands (integrin alpha2beta1 and alpha3beta1 components), can reveal histoarchitectural differences which distinguish these two entities.METHODS AND RESULTS: Five cases of ACC and five cases of PLGA from the archives of the Oral Pathology Department of the School of Dentistry of the S?o Paulo University were submitted to immunostaining with the antibodies to collagen IV, laminin, and integrins alpha2beta1 and alpha3beta1 using the streptavidin-biotin-peroxidase technique. Positive and negative controls were included. PLGA showed a thin line of collagen IV and laminin surrounding structures composed of a single cell layer. Integrins were expressed as a widespread and granular pattern. A thick line of collagen and laminin was observed around the neoplastic structures of ACC. Both integrins were expressed in intercellular spaces and around luminal spaces of tubular structures.CONCLUSIONS: Collagen IV and laminin, and their integrin ligands, are useful in demonstrating that neoplastic ductal units of PLGA are composed of a single cell layer, being distinct from ACC which contains structures composed of two layers of neoplastic cells.
Adenocarcinoma Carcinoma, Adenoid Cystic