Can neurons make up a brain tumour?

No, neurons cannot make up a brain tumor. A brain tumor is an abnormal growth of cells that can occur in any part of the brain or central nervous system, including the meninges and/or other supportive tissues. Although tumors can contain various types of cells, they are not made up solely of neurons – rather, they typically consist of multiple cell types derived from neural progenitors, glial cells, Schwann cells and fibroblasts. Moreover, these tumors can be composed primarily of one type or several different types according to their origin and stage at which they develop.

In addition to this cellular diversity within a tumor mass itself, it is important to note that there are also many non-tumorigenic lesions (such as cysts) which do not represent true neoplasms but may nonetheless lead to considerable dysfunction due to their mass effect on surrounding normal tissues. The only way for a tumor originating from within the CNS parenchyma to be constituted solely by neurons is if those cells were transformed in some manner into cancerous ones -which occurs very rarely indeed- thus explaining why most diagnoses involving primary neoplasms within the CNS will usually lack neuronal components upon microscopic examination.