| Brain Tumor | | | | confusing. Some pathologists advocate abandoning |
| A brain tumor — primary or secondary — can | | | | the traditional morphologically-based classifications |
| cause a variety of signs and symptoms because it | | | | such as medulloblastoma in favor of a terminology |
| can directly press on or invade brain tissue. This can | | | | that relies more extensively on the phenotypic |
| damage or destroy areas responsible for sight, | | | | characteristics of the tumor. |
| movement, balance, speech, hearing, memory or | | | | Primary Brain Tumor |
| behavior. Brain tumor symptoms vary from patient to | | | | Astrocytomas — these tumors arise from small, |
| patient, and most of these symptoms can also be | | | | star-shaped cells called astrocytes. They may grow |
| found in people who do NOT have brain tumors. | | | | anywhere in the brain or spinal cord. In adults, |
| | | | astrocytomas most often arise in the cerebrum. In |
| Classification | | | | children, they occur in the brain stem, the cerebrum |
| HISTOPATHOLOGIC CLASSIFICATION — Primary | | | | and the cerebellum. A grade III astrocytoma is |
| brain tumors are classified by light microscopy | | | | sometimes called anaplastic astrocytoma. A grade IV |
| according to their predominant cell type and graded | | | | astrocytoma is usually called glioblastoma multiforme. |
| based upon the presence or absence of standard | | | | Brain stem gliomas — These tumors occur in the |
| pathologic features. Historical attempts at developing | | | | lowest, stem-like part of the brain. The brain stem |
| a classification system for brain tumors date back to | | | | controls many vital functions. Most brain stem gliomas |
| the 1830s. The German pathologist Rudolf Virchow | | | | are high-grade astrocytomas. |
| first introduced the term "glioma" in 1860. Virchow | | | | Secondary Brain Tumor |
| was also the first to attempt a correlation of | | | | Metastatic brain tumors originate from malignant |
| microscopic to macroscopic features of CNS tumors. | | | | tumors located primarily in other organs. Their |
| Cellular Classification-He classification of brain tumors | | | | incidence is higher than that of primary brain tumors. |
| is based on both histopathological characteristics and | | | | The most frequent types of metastatic brain tumors |
| location in the brain. Undifferentiated neuroectodermal | | | | originate in the lung skin (malignant melanoma, kidney |
| tumors of the cerebellum have historically been | | | | (hypernephroma, breast (breast carcinoma), and |
| referred to as medulloblastomas, while tumors of | | | | colon (colon carcinoma). These tumor cells reach the |
| identical histology in the pineal region would be | | | | brain via the blood-stream. |
| diagnosed as pineoblastomas. The nomenclature of | | | | Some non-tumoral masses and lesions can mimic |
| pediatric brain tumors is controversial and potentially | | | | tumors of the central nervous system. |