Salivary gland tumours: diagnostic challenges and an update on the latest WHO classification
Paul M. Speight, A.W. Barrett
Abstract
Salivary gland tumours are one of the most difficult areas of diagnostic pathology, with significant morphological diversity and many overlapping features. The latest WHO classification has attempted to simplify the classification but there are still more than 30 tumours for the pathologist to grapple with. These include two new entities – secretory carcinoma and sclerosing polycystic adenosis – and a number of name changes. Most controversial is the removal of "low grade" from polymorphous low-grade adenocarcinoma and the inclusion of intraductal carcinoma as a unifying entity. There are also more nuanced changes in categorisation or terminology that may influence the way a diagnostic report is written. Despite advances in immunohistochemistry and molecular pathology, the WHO still use histomorphology as the primary basis for classification. However, morphological similarities can make diagnosis difficult without the assistance of ancillary techniques. In this short review we describe these changes in the latest WHO classification, discuss particular areas of diagnostic difficulty, and suggest some useful antibodies that can be used to assist diagnosis.