Malignant neoplasms of parotid gland

**Definition:** Salivary gland tumours can show a striking range of morphological diversity between different tumour types and sometimes within an individual tumour mass. In addition, hybrid tumours, dedifferentiation and the propensity for some benign tumours to progress to malignancy can confound histopathological interpretation. These features, together with the relative rarity of a number of tumours, can sometimes make diagnosis difficult, despite the abundance of named tumour entities. The increasing use of pre-operative fine needle aspiration biopsies also needs to be taken into account, as artifactual changes may be superimposed on the tumours. Unfortunately, the morphological variability of these tumours is mirrored by the immunocytochemical profiles, so that special stains are rarely useful in routine diagnosis of salivary gland epithelial neoplasms.

**Exclusions:** - Malignant mesenchymal neoplasms