Role of Ancillary Techniques in the Differential Diagnosis of Salivary Gland Carcinomas

Paiva-Correia A, Hellquist H, Apolónio J, Castelo-Branco P. Role of ancillary techniques in the differential diagnosis of salivary gland carcinomas. The diagnosis of salivary gland carcinomas (SGC) rests mainly on histology, but immunohistochemical and molecular investigations are often necessary for differential diagnosis. This review is primarily aimed as a tool for pathologists in non-specialised head and neck hospitals who encounter a limited number of SGC annually. The use of testing an initial antibody panel, which may comprise both positive and negative expression for a suspected entity, and examples of different panels are outlined. We also focused on acinic cell carcinoma (AcCC), which is positive for DOG1 and negative for mammaglobin, whilst secretory carcinoma (SC) is positive for mammaglobin and negative for DOG1. In addition, the exclusive expression of androgen and HER2 in salivary duct carcinoma (SDC) and its use for differential diagnosis are also addressed. This review also highlights the particularities of mucoepidermoid carcinoma (MEC) and its negativity for S100 and SOX10, which distinguishes it from some of its mimics. In laboratories with limited access to antibodies for SGC, we recommend inclusion of mammaglobin. The use of molecular techniques for the diagnosis of MEC (MAML2), SC (ETV6), adenoid cystic carcinoma (MYB), and AcCC (NR4A3) is discussed. We highlight the role of commonly available antibodies for the histological classification of SGC.