Neurosarcoidosis: This is a condition where sarcoidosis, a disease characterized by the growth of granulomas (inflammatory cells) in various parts of the body, affects the nervous system. It can mimic brain tumors in presentation and imaging, making it a primary consideration in this differential diagnosis due to its direct involvement of the CNS and potential to cause mass-like lesions.

Multiple Sclerosis (MS): MS is an autoimmune disease that affects the brain and spinal cord, leading to demyelination, inflammation, and a wide range of neurological symptoms. It can present with lesions that might be mistaken for tumors on imaging studies.
Lymphoma (Primary Central Nervous System Lymphoma, PCNSL): Although a true malignancy, PCNSL can sometimes be considered in the differential for inflammatory conditions due to its potential for dramatic response to corticosteroids, which can temporarily reduce swelling and symptoms, mimicking an inflammatory process.
Tuberculoma: A tuberculoma is a mass-like lesion caused by tuberculosis infection in the brain. It can mimic brain tumors and is an important consideration, especially in regions where TB is common.

CNS Vasculitis: Inflammation of the blood vessels in the CNS can lead to a variety of symptoms and imaging findings that might mimic tumors. Missing this diagnosis could lead to severe consequences, including stroke and death.
Infectious Abscess: A brain abscess is a collection of pus, immune cells, and other material in the brain, usually from a bacterial or fungal infection. It is critical to identify and treat promptly to avoid severe complications or death.
Paraneoplastic Syndromes: These are rare disorders that are triggered by an altered immune system response to a neoplasm, which can affect the CNS and mimic other conditions, including tumors and inflammatory diseases.

Histiocytosis (e.g., Langerhans Cell Histiocytosis): A rare disorder in which the body accumulates too many immature Langerhans cells (a type of histiocyte or immune cell). It can affect the CNS and present with mass-like lesions.
Rosai-Dorfman Disease: A rare and benign histiocytic disorder that can involve the CNS and present with mass lesions, although it more commonly affects lymph nodes.
** Erdheim-Chester Disease**: A rare form of histiocytosis that can involve the CNS, among other systems, and present with a variety of neurological symptoms and imaging findings.