Untitled

Central Nervous System Tumors

Overview of CNS Tumors

  • CNS tumors can be metastatic (50%) or primary (50%).

  • Common Metastatic Sources:

    • Lung cancer

    • Breast cancer

    • Kidney cancer

  • Presentation: Metastatic lesions often appear as multiple well-circumscribed lesions, primarily at the gray-white junction.

Classification of Primary CNS Tumors

  • Primary CNS tumors are classified by cell type:

    • Malignant primary tumors are typically locally destructive, but do not usually spread outside CNS.

Cell Types in CNS

  • CNS consists of:

    • 50% Neurons

    • 50% Glial Tissue (supports neurons)

    • Astrocytes: Form the blood-brain barrier.

    • Oligodendrocytes: Myelinate axons.

    • Ependymal Cells: Line the ventricular spaces.

    • Meningothelial Cells: Surround the brain.

  • These cell types can produce tumors in both children and adults.

Key Tumors in CNS

Astrocytic Tumors

  • Pilocytic Astrocytoma:

    • Description: Benign tumor in children.

    • Location: Usually in the cerebellum.

    • Key Imaging: Cystic lesion with a mural nodule.

    • Histological Features: Rosenthal fibers (thick eosinophilic processes).

    • GFAP Positive.

  • Glioblastoma Multiforme:

    • Description: Highly malignant tumor in adults; most common CNS tumor.

    • Location: Cerebral hemispheres.

    • Characteristic Association: Crosses the corpus callosum; sometimes called butterfly glioma.

    • Histological Features:

    • Necrosis: Large necrotic areas.

    • Pseudo Palisading: Living cells at the edge of necrosis.

    • Endothelial Cell Proliferation.

    • Intermediate Filament: GFAP positive.

Oligodendrocytic Tumors

  • Oligodendroglioma:

    • Description: Malignant tumor of oligodendrocytes.

    • Key Features: Often calcified tumor in the white matter (frontal lobe) that typically presents with seizures.

    • Histological Features: Fried egg appearance (cytoplasm resembles fried eggs).

Ependymal Tumors

  • Ependymoma:

    • Description: Malignant tumor from ependymal cells (childhood)

    • Location: Usually in the fourth ventricle, grows into ventricular space blocking CSF flow, leading to hydrocephalus.

    • Histological Features: Perivascular pseudorosettes.

Meningeal Tumors

  • Meningioma:

    • Description: Benign tumor of arachnoid cells; most common benign tumor in adults.

    • Demographics: Predominantly seen in adult females.

    • Key Features: Attached to dura, compresses cortex causing seizures (compression, not invasion).

    • Histological Features: Whorled pattern (often with calcified somoma bodies).

Neuroectodermal Tumors

  • Medulloblastoma:

    • Description: Malignant tumor derived from granular cells of the cerebellum, often seen in children.

    • Histological Features: Small round blue cells with Homer-Wright rosettes; rapid growth, poor prognosis, drop metastases through CSF.

Craniopharyngioma

  • Description: Tumor from Rathke’s pouch remnants; occurs in children and young adults.

    • Location: Supratentorial mass (near optic chiasm).

    • Symptoms: Can cause bitemporal hemianopsia due to optic chiasm compression.

    • Imaging: Often calcified; benign but may recur after resection.