Mass effect describes how a lesion is pushing on nearby structures — bulging into them, displacing them, or compressing surrounding tissue.
Mass effect is a finding on a scan; the symptoms depend on what is being compressed (headache and nausea in the brain, swallowing problems near the throat, breathing issues near the airway).
Imaging shows the size of the lesion, what it is pressing on, how much displacement is present, and whether it is causing additional changes such as midline shift or hydrocephalus.
CT and MRI both show mass effect; MRI gives more detail about how the lesion relates to surrounding soft tissue.
Treatment targets the underlying lesion (tumour, abscess, bleed, oedema) and may include steroids to reduce swelling, surgical decompression, or other specific therapy.
This entry explains the word. If it appeared on your report, the next step is getting that report interpreted for your case.
