Background
Salivary gland neoplasms exhibit a diverse array of morphological features that often pose significant diagnostic difficulties.
Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy in all age groups, while adenoid cystic carcinoma (AdCC) accounts for 25% of all primary salivary carcinomas. Considerable progress has been made in the characterisation of genomic alterations in these tumours (MAML2 in MEC, MYB in AdCC).
FISH is a molecular test requiring little tissue and can quickly confirm diagnoses thus serving as a valuable diagnostic tool. The aim of the present study was to establish a preliminary salivary FISH platform, beginning with MAML2 and MYB.
Methods: 30 cases were tested, 15 for MAML2 rearrangement and 15 for MYB. For EQA, an inter-laboratory comparison was performed with an accredited laboratory.
Results: While some cases had typical morphological features of MEC and AdCC, others presented a significant diagnostic challenge, where detection of either a MAML2 or MYB rearrangement was instrumental in confirming a definitive diagnosis of MEC or AdCC. FISH was negative in the morphologic mimics of MEC.
Conclusion: FISH testing is a quick accurate test, useful in diagnostically challenging salivary gland neoplasms. FISH testing for MAML2 and MYB has been successfully established in St. James’s Hospital and is available as a valuable adjunctive diagnostic tool for salivary gland neoplasms.
Giuseppa Castriciano1,2, Louise Curran1,2, Bijal Shah1,2, Peter Molony1,2, Roisin O’Connor1-4, Esther O’Regan1-4
1 Department of Histopathology, St. James’s Hospital, Dublin
2 Trinity St. James’s Cancer Institute, Dublin
3 Division of Oral & Maxillofacial Surgery, Oral Medicine & Oral Pathology, Trinity College, Dublin
4 Discipline of Histopathology, School of Medicine, Trinity College Dublin