What is the differential for this mass?
A solid apparently solitary intra-axial mass located at the grey-white matter junction with surrounding oedema in a 70 year old patient is most likely going to be a metastasis or a glioma (WHO grade III or IV). Depending on the demographic a focus of infection (e.g. tuberculoma) or even lymphoma can have similar appearances, although both are comparatively rare.
True or false: Finding a solitary mass makes metastatic disease unlikely.
False. Approximately 50% of cerebral metastases are solitary.
What features favour a metastasis over a glioblastoma?
Solid, spherical enhancing mass at the grey-white matter junction. Glioblastomas tend to have necrotic / non-enhancing centres and are centred on the white matter. They are usually also more irregular in shape with a predilection to spread along borders of the ventricles (subependymal spread).
What are the most common primary malignancies to metastasis to the brain?
80% of brain metastases can be accounted for by five primary tumours: lung cancer, breast cancer, melanoma, renal cell carcinoma, gastrointestinal tract adenocarcinomas (the majority being colorectal carcinomas).
The enhancing mass ( * ) is surrounded by vasogenic oedema (blue dotted line) which is confined to the white matter.