OVERVIEW
This page is dedicated to covering the important radiological finding of a ring enhancing lesion.
WHAT IS IT?
A ring enhancing lesion refers to a finding that is noted on a contrast head CT scan/MRI with IV contrast. It refers to a lesion whose edges “enhance” (increase in signal) upon the administration of IV contrast (effectively making it look like a “ring”).
![This is an axial CT scan of the brain. The pane on the left is without contrast, and the pane on the right is after IV contrast administration. The ring enhancing lesion can be clearly seen (source).](http://www.stepwards.com/wp-content/uploads/2016/10/Fig-1-Plain-and-contrast-enhanced-cranial-computed-tomography-showing-a-ring-enhancing-1.png)
DIFFERENTIAL DIAGNOSIS FOR THIS FINDING
When seeing a ring enhancing lesion, it is important too keep in mind that there are some important conditions to keep in mind in the differential.
- Toxoplasmosis: (disease page, radiology page)
- Primary CNS lymphoma: (disease page, radiology page)
- Cerebral abscess: (radiology page)