Classification of Brain Tumor

By Peter Sams

A brain tumor — primary or secondary — can cause a variety of signs and symptoms because it can directly press on or invade brain tissue. This can damage or destroy areas responsible for sight, movement, balance, speech, hearing, memory or behavior. Brain tumor symptoms vary from patient to patient, and most of these symptoms can also be found in people who do NOT have brain tumors.

Therefore, the only sure way to tell if you have a brain tumor or not is to see your doctor and get a brain scan. The growth of abnormal cells in the tissues of the brain. Brain tumors can be benign (non-cancerous) or malignant. A primary brain tumor is a group (mass) of abnormal cells that start in the brain. This article focuses on primary brain tumors in adults. Brain tumors encompass neoplasms that originate in the brain itself (primary brain tumors) or involve the brain as a metastatic site. Brain tumors (metastatic brain tumors), which are malignant, are more common. These tumors result from cancer that started elsewhere in the body and spread (metastasized) to the brain.

Classification

HISTOPATHOLOGIC CLASSIFICATION — Primary brain tumors are classified by light microscopy according to their predominant cell type and graded based upon the presence or absence of standard pathologic features. Historical attempts at developing a classification system for brain tumors date back to the 1830s. The German pathologist Rudolf Virchow first introduced the term "glioma" in 1860. Virchow was also the first to attempt a correlation of microscopic to macroscopic features of CNS tumors.

Cellular Classification-He classification of brain tumors is based on both histopathological characteristics and location in the brain. Undifferentiated neuroectodermal tumors of the cerebellum have historically been referred to as medulloblastomas, while tumors of identical histology in the pineal region would be diagnosed as pineoblastomas. The nomenclature of pediatric brain tumors is controversial and potentially confusing. Some pathologists advocate abandoning the traditional morphologically-based classifications such as medulloblastoma in favor of a terminology that relies more extensively on the phenotypic characteristics of the tumor.

Primary Brain Tumor

Astrocytomas — these tumors arise from small, star-shaped cells called astrocytes. They may grow anywhere in the brain or spinal cord. In adults, astrocytomas most often arise in the cerebrum. In children, they occur in the brain stem, the cerebrum and the cerebellum. A grade III astrocytoma is sometimes called anaplastic astrocytoma. A grade IV astrocytoma is usually called glioblastoma multiforme.

Brain stem gliomas — These tumors occur in the lowest, stem-like part of the brain. The brain stem controls many vital functions. Most brain stem gliomas are high-grade astrocytomas.

Secondary Brain Tumor

Metastatic brain tumors originate from malignant tumors located primarily in other organs. Their incidence is higher than that of primary brain tumors. The most frequent types of metastatic brain tumors originate in the lung skin (malignant melanoma, kidney (hypernephroma, breast (breast carcinoma), and colon (colon carcinoma). These tumor cells reach the brain via the blood-stream.
Some non-tumoral masses and lesions can mimic tumors of the central nervous system. These include tuberculosis of the brain, cerebral abscess (commonly in toxoplasmosis), and hamartomas