Biphasic salivary gland neoplasm

By Jason Wasserman MD PhD FRCPC
December 2, 2024

A biphasic salivary gland neoplasm is a tumour that arises in one of the salivary glands. It is called biphasic because it comprises two distinct populations of cells: luminal cells (ductal cells) and abluminal cells (basal cells or myoepithelial cells). The luminal cells are typically large round or cuboidal-shaped cells that connect to form round structures called ducts or glands. The abluminal cells are smaller and often found on the outside or periphery of the ducts and glands. Myoepithelial-type abluminal cells are usually described as spindle cells because they are long and thin. Several different kinds of salivary gland tumours can be characterised as biphasic salivary gland neoplasm.

When is this diagnosis made?

The diagnosis of biphasic salivary gland neoplasm is typically used after a biopsy has been performed and a small sample of the tumour has been examined under the microscope by a pathologist. The small sample allows the pathologist to determine that the tumour is biphasic, which means it comprises two types of cells (luminal and abluminal), but a more definitive or final diagnosis cannot be reached. A definitive or final diagnosis will be provided after the entire tumour is removed and examined. In some situations, the term biphasic salivary gland neoplasm may also be used even after the whole tumour has been removed while the pathologist waits for additional tests (for example, next-generation sequencing) to help confirm the diagnosis.

Is a biphasic salivary gland neoplasm benign or malignant?

The term biphasic salivary gland neoplasm describes a group of salivary gland tumours that include both benign (noncancerous) and malignant (cancerous) tumours.

What does it mean if my report says that something is “favoured”?

Pathologists use the term favoured when multiple diagnoses are being considered, but there is one diagnosis they think is most likely. For example, the diagnosis “biphasic salivary gland neoplasm, favour pleomorphic adenoma” means that the microscopic features were in keeping with a biphasic salivary gland neoplasm (a group which includes many types of tumours) but that the pathologist thinks pleomorphic adenoma (a specific type of salivary gland tumour) is the most likely diagnosis.

What is the most common type of biphasic salivary gland neoplasm?

The most common type of biphasic salivary gland neoplasm is pleomorphic adenoma. Pleomorphic adenoma can arise in any of the salivary glands, although it is most commonly found in the parotid gland.

Other benign salivary gland tumours include:

• Basal cell adenoma
• Intercalated duct adenoma
• Sclerosing polycystic adenoma

What is the most common type of malignant biphasic salivary gland neoplasm?

The most common type of malignant biphasic salivary gland neoplasm is adenoid cystic carcinoma.

Other malignant salivary gland tumours include:

• Acinic cell carcinoma
• Basal cell adenocarcinoma
• Intraductal carcinoma
• Epithelial-myoepithelial carcinoma
• Sclerosing microcystic adenocarcinoma

About this article

Doctors wrote this article to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report. For a complete introduction to your pathology report, read this article.