Polymorphous low-grade adenocarcinoma and adenoid cystic carcinoma: distinct architectural composition revealed by collagen IV, laminin and their integrin ligands (alpha 2 beta 1 and alpha 3 beta 1)

Aims: Polymorphous low-grade adenocarcinoma (PLGA) and adenoid cystic carci noma (ACC) are malignant salivary gland tumours bearing many similar histol ogical patterns. This study was undertaken to show how the presence and dis tribution of collagen IV and laminin, and their ligands (integrin alpha 2 b eta 1 and alpha 3 beta 1 components), can reveal histoarchitectural differe nces which distinguish these two entities. Methods and results: Five cases of ACC and five cases of PLGA from the arch ives of the Oral Pathology Department of the School of Dentistry of the Sao Paulo University were submitted to immunostaining with the antibodies to c ollagen IV, laminin, and integrins alpha 2 beta 1 and alpha 3 beta 1 using the streptavidinbiotin-peroxidase technique. Positive and negative controls were included. PLGA showed a thin line of collagen IV and laminin surround ing structures composed of a single cell layer. Integrins were expressed as a widespread and granular pattern. A thick line of collagen and laminin wa s observed around the neoplastic structures of ACC. Both integrins were exp ressed in intercellular spaces and around luminal spaces of tubular structu res. Conclusions: Collagen IV and laminin, and their integrin ligands, are usefu l in demonstrating that neoplastic ductal units of PLGA are composed of a s ingle cell layer, being distinct from ACC which contains structures compose d of two layers of neoplastic cells.