Extraparenchymal extension

by Jason Wasserman MD PhD FRCPC
September 19, 2022

What does extraparenchymal extension mean?

The term extraparenchymal extension is used to describe the spread of tumour cells into the tissues surrounding an organ. In order to be considered extraparenchymal extension, the tumour must have started within the parenchyma of an organ. As a result, tumours that start in the connective tissue surrounding an organ cannot be assessed for extraparenchymal extension. The term extraparenchymal extension is commonly used when describing salivary gland tumours, however, it can be used for tumours arising in other organs as well.

Why is extraparenchymal extension important?

Extraparenchymal extension is important because it is associated with a higher risk that the tumour will regrow in the same location after surgery. Doctors call this a local recurrence. For some types of tumours, extraparenchymal extension is also associated with a higher risk that tumour cells will metastasize (spread) to other body parts. For these reasons, extraparenchymal extension is one of several criteria used when determining the pathologic tumour stage (pT).