CNS Tumors - PDF

## CNS TUMORS ### I. BASIC PRINCIPLES * Can be metastatic (50%) or primary (50%) * Metastatic tumors characteristically present as multiple, well-circumscribed lesions at the gray-white junction. * Lung, breast, and kidney are common sources. * Primary tumors are classified according to cell ty...

## CNS TUMORS ### I. BASIC PRINCIPLES * Can be metastatic (50%) or primary (50%) * Metastatic tumors characteristically present as multiple, well-circumscribed lesions at the gray-white junction. * Lung, breast, and kidney are common sources. * Primary tumors are classified according to cell type of origin (e.g., astrocytes, meningothelial cells, ependymal cells, oligodendrocytes, or neuroectoderm). * In adults, primary tumors are usually supratentorial. * Most common tumors in adults are glioblastoma multiforme, meningioma, and schwannnoma. * In children, primary tumors are usually infratentorial. ### II. GLIOBLASTOMA MULTIFORME (GBM) * Malignant, high-grade tumor of astrocytes * Most common primary malignant CNS tumor in adults * Usually arises in the cerebral hemisphere; characteristically crosses the corpus callosum ('butterfly' lesion) * Characterized by regions of necrosis surrounded by tumor cells (pseudopalisading) and endothelial cell proliferation; tumor cells are GFAP positive. * Poor prognosis ### III. MENINGIOMA * Benign tumor of arachnoid cells * Most common benign CNS tumor in adults. * More commonly seen in women; rare in children. * May present as seizures; tumor compresses, but does not invade, the cortex. * Imaging reveals a round mass attached to the dura. * Histology shows a whorled pattern; psammoma bodies may be present. ### IV. SCHWANNOMA * Benign tumor of Schwann cells * Involves cranial or spinal nerves; within the cranium, most frequently involves cranial nerve VIII at the cerebellopontine angle (presents as loss of hearing and tinnitus) * Tumor cells are S-100 positive. * Bilateral tumors are seen in neurofibromatosis type 2. ### V. OLIGODENDROGLIOMA * Malignant tumor of oligodendrocytes * Imaging reveals a calcified tumor in the white matter, usually involving the frontal lobe; may present with seizures * 'Fried-egg' appearance of cells on biopsy. ### VI. PILOCYTIC ASTROCYTOMA * Benign tumor of astrocytes * Most common CNS tumor in children; usually arises in the cerebellum * Imaging reveals a cystic lesion with a mural nodule ### VII. MEDULLOBLASTOMA * Malignant tumor derived from the granular cells of the cerebellum (neuroectoderm) * Usually arises in children * Histology reveals small, round blue cells; Homer-Wright rosettes may be present. * Poor prognosis; tumor grows rapidly and spreads via CSF. * Metastasis to the cauda equina is termed 'drop metastasis.' ### VIII. EPENDYMOMA * Malignant tumor of ependymal cells; usually seen in children * Most commonly arises in the 4th ventricle; may present with hydrocephalus * Perivascular pseudorosettes are a characteristic finding on biopsy. ### IX. CRANIOPHARYNGIOMA * Tumor that arises from epithelial remnants of Rathke's pouch * Presents as a supratentorial mass in a child or young adult; may compress the optic chiasm leading to bitemporal hemianopsia * Calcifications are commonly seen on imaging (derived from "tooth-like" tissue). * Benign, but tends to recur after resection. ### FUNDAMENTALS OF PATHOLOGY * Most common tumors in children are pilocytic astrocytoma, ependymoma, and medulloblastoma. * Primary malignant CNS tumors are locally destructive, but rarely metastasize ### CENTRAL NERVOUS SYSTEM PATHOLOGY * Biopsy shows Rosenthal fibers and eosinophilic granular bodies; tumor cells are GFAP positive. Fig. 17.14 Huntington disease - A, Degeneration of caudate nucleus. B, Normal caudate nucleus for comparison. Fig. 17.15 Spongiform encephalopathy Fig. 17.16 Glioblastoma multiforme - A, 'Butterfly' lesion. B, Pseudopalisading. Fig. 17.17 Meningioma Fig. 17.18 Oligodendroglioma Fig. 17.19 Pilocytic astrocytoma - A, Cystic lesion with mural nodule. B, Rosenthal fibers. Fig. 17.20 Ependymoma