The purpose of this study is to evaluate the sensitivity and specificity of "A-PROTEIN" levels in patients with brain tumors. A-PROTEIN levels will be analyzed both pre and post treatment. Levels in blood and/or cerebrospinal fluid (CSF) will be analyzed and correlated with the underlying diagnosis and outcome.

• Patients will be identified at the time of presentation to their neurologist, neurosurgeon or oncologist.
• Blood or cerebrospinal fluid will be collected for this study only when they are being collected for other reasons before and after each surgery. Samples will also be collected after any event such as significant change in symptoms or radiographic progression.
• Once the patients condition has been stabilized, samples will be take at regular intervals of >= 1 month. The duration of this study is 24 months.

Inclusion Criteria:

• All patients with possible malignant or benign lesions of the central nervous system will be included.
• There are no restrictions with respect to treatment protocols or prior therapy.
• Patients will be identified after presentation to the neurosurgical, neurological or oncologic services at participating centers. Any patient with evidence of a central nervous system tumor will be eligible. Individuals without evidence of CNS tumors are also eligible, in order to provide blinded controls.
• A signed informed consent will be requested and required for participation.
• There is no age, sex, or ethnic origin restrictions in this protocol. Patients who choose not to participate in the study will continue to have their regular care as defined by their treating team. Patients who speak foreign languages are eligible as long a translator can be found to ensure proper consent has been obtained.

Exclusion Criteria: There are no exclusion criteria for this study.

Patients will be identified at the time of presentation to their neurologist, neurosurgeon or oncologist