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- Role of ancillary techniques in the differential diagnosis of salivary gland carcinomasPublication . Paiva Correia, Antonio; Hellquist, Henrik; Apolónio, Joana; Castelo-Branco, PedroPaiva-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.
- Methylation status of the telomerase reverse transcriptase promoter in parotid tumours and adjacent parotid gland tissue: a pilot study on the implications for recurrence and development of malignancyPublication . Paiva Correia, Antonio; Apolónio, Joana; Nadal, Alfons; Brandão, José Ricardo; Silva, Nádia; Machado, Bianca; Archilla, Ivan; Castelo-Branco, Pedro; Hellquist, HenrikBackground/Objectives: The methylation of the hypermethylated oncological region (THOR) of human telomerase reverse transcriptase (hTERT) may forecast tumour aggressiveness. This pilot study aimed to evaluate THOR methylation as a potential biomarker for recurrence/malignant transformation in salivary gland pleomorphic adenomas (PA). Methods: THOR methylation was assessed by quantitative pyrosequencing in 96 parotid tissue samples (benign and malignant), including non-neoplastic parotid tissue, PA, recurrent PA (rPA), and carcinomas, along with their adjacent tissues. TERT promoter mutations (TPMs) were analysed by Sanger sequencing. Results: THOR methylation significantly differed across the seven groups. Malignant tissues showed higher THOR methylation than non-neoplastic tissues, whereas benign tumours showed no significant difference from non-neoplastic tissue. THOR methylation in rPA was closer to carcinoma than to normal tissue, similar in rPA and tissues adjacent to rPA, and higher in tissues adjacent to carcinomas than in non-neoplastic tissues. A subset of PA-adjacent tissues showed epigenetic alterations, suggesting an increased risk of recurrence or malignant transformation (5–15%). No TPMs were detected. Conclusions: THOR methylation may add information to differentiate normal from carcinogenic tissues and, as such, may be included in a biomarkers panel. Epigenetic alterations in PA-adjacent tissues with normal histology highlight the need for improved diagnostic markers.