Primary CNS Lymphoma

Primary CNS lymphoma has association with HIV/AIDS and immunocompromised patients, and does not have systemic nodal disease at diagnosis. It is typically (95%) a B-cell non Hodgkin lymphoma (NHL), and is usually supratentorial (90%), having a predilection for deep grey matter of the frontal and parietal lobes, clustering around the ventricles. It also has a predisposition for crossing the corpus callosum, with the differential being a butterfly glioma.
This is in contrast to secondary CNS lymphoma (also typically NHL) which more commonly involves the leptomeninges but it is uncommonly detectable on CT/MRI
Primary CNS lymphoma accounts for approximately 1% of all extranodal lymphomas, and 1-7% of intracranial tumours but has increasing incidence. This is partially due to increasing rates of immunocompromise but an increase is also seen in the non immunocompromised population.
Differential diagnosis includes:
Cerebral toxoplasmosis
Tumefactive MS
Cerebral abscess
GBM
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Credit: Dr Frank Gaillard
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