CNS Pathology Lab 2: Neurodegenerative Diseases

CNS Pathology Lab

Gross Features of CNS Pathology

• Cerebral atrophy is characterized by narrowed gyri and widened sulci, most prominent in the frontal and parietal regions.
• Pallor of substantia nigra is due to degeneration and loss of dopaminergic neurons.

Alzheimer's Disease

• Characterized by diffuse plaques and neuritic plaques.
• Neurofibrillary tangles are present.

Parkinson's Disease

• Lewy body in a neuron from the substantia nigra is composed of α-synuclein.

Huntington's Disease

• Atrophy of the striatum (caudate, putamen) and ventricular dilation occur.
• Caudate nucleus demonstrates loss of neurons along with gliosis.
• Intranuclear inclusions are present.

Multiple Sclerosis

• MS plaques are characterized by unstained regions of demyelination around the fourth ventricle.
• Luxol fast blue-PAS stain is used to stain myelin.

Gliomas

• Diffuse glioma appears as a cystic mass in the peripheral cerebral hemisphere with indistinct borders.
• High-grade glioma (glioblastoma, grade 4) is characterized by:
  • Large destructive lesion with areas of necrosis and hemorrhage.
  • Marked cellularity, with hyperchromatism and pleomorphism.
  • Prominent vascularity along with palisading necrosis.
• Pilocytic astrocytoma (circumscribed glioma, grade 1) is characterized by:
  • Mild cellularity with elongated cells and Rosenthal fibers.
  • Typically occurs in the cerebellum in children.

Meningioma

• Appears as a compressive mass beneath the dura, compressing the underlying cerebral hemisphere.
• Characterized by:
  • Whorled nests of cells (meningiothelial growth pattern).
  • Many small vessels, leading to significant vascularity with angiographic procedures.
  • Psammoma bodies are present.

Ependymoma

• Typically occurs in the ventricular system in children.
• Can produce obstructive hydrocephalus.
• Characterized by:
  • Rosettes/canals with long, delicate processes extending into a lumen (pseudo rosette).
  • Cells arranged around a central vascular space.

Medulloblastoma

• Typically occurs in the posterior fossa near the midline of the cerebellum.
• Characterized by:
  • Small round blue cells with Homer Wright rosettes.
  • Common in children.

Schwannoma

• Firm mass arises in the peripheral nerve (e.g., acoustic (eighth cranial) nerve at the cerebellopontine angle).
• Characterized by:
  • "Antoni A" pattern with more cellular, palisading nuclei surrounding pink areas (Verocay bodies).
  • "Antoni B" pattern with a looser stroma, fewer cells, and myxoid change.