Neuropathology tumours

The article covers CNS tumours, including Brain tumours. They are relatively common and mostly real badness. Tumours are a large part of neuropathology.

The article also includes peripheral nerve sheath tumours.

Brain tumours

Adult

Four most common types of brain tumours:

1. Metastatic brain tumours (barely edges out primary tumours)
   • Lung (most common),
   • Breast,
   • Melanoma,
   • Renal cell carcinoma (RCC).
2. Glioblastoma aka glioblastoma multiforme.
3. Anaplastic (malignant) astrocytoma.
4. Meningioma.

Children

1. Astrocytoma.
2. Medulloblastoma.
3. Ependymoma.

Astrocytomas

• Pilocytic astrocytomas (WHO Grade I).
• Dysembryoplastic neuroepithelial tumour (DNT), (WHO Grade I).
• Low-grade (diffuse) astrocytomas (Grade II).
• Anaplastic astrocytomas (Grade III).
• Glioblastoma (Grade IV).

Features:

• Nuclear pleomorphism.
• Mitotic figures.
• Microvascular proliferation or necrosis with pseudopalisading tumour cells.
  • Pseudopalisading tumour cells = high tumour cell density adjacent to regions of necrosis; palisade = a fence of pales forming a defense barrier or fortification.

Pilocytic astrocytoma

General

• Low-grade astrocytoma.

Gross

• Do NOT smear.

Microscopic

• Rosenthal fibres - key feature.
  • Image: Rosenthal fibres (WC).

DDx (of Rosenthal fibers):

• Chronic reactive gliosis.
• Subependymoma.
• Ganglioma.
• Alexander's disease (rare leukodystrophy).

Oligodendroglioma

• Arise from oligodendrocytes.

Microscopic

Features:

• Highly cellular lesion composed of:
  • Cells resembling fried eggs (oligodendrocytes) with:
    • Distinct cell borders.
    • Moderate-to-marked nuclear atypia.
    • Clear cytoplasm.
  • Acutely branched capillary sized vessels - "chicken-wire" like appearance.
    • Abundant, delicate appearing; may vaguely resemble a paraganglioma at low power.
• Calcifications. - important feature.

Images:

• Oligodendroglioma high mag. (WC).
• Oligodendroglioma low mag. (WC).

Peripheral nerve sheath tumours

A classification:

• Benign:
  • Schwannoma.
  • Neurofibroma.
  • Perineurioma.
  • Traumatic neuroma.
• Malignant:
  • Malignant peripheral nerve sheath tumour (MPNST).

Schwannoma

• Tumour of tissue surrounding a nerve.
  • Axons adjacent to the tumour are normal... but may be compressed.

Histology

Antoni tissue:

Antoni A

• Cellular.
• 'Fibrillary, polar, elongated'.

Comment: May look somewhat like scattered matchsticks.

Antoni B

• Loose microcystic tissue.
• Adjacent to Antoni A.

Micrographs:

• Antoni A (pathguy.com).
• Antoni A & Antoni B side-by-side (ajnr.org).

Neurofibroma

General:

• Composed of Schwann cells, axons, fibrous material.

Appearance/morphology:

• Plexiform growth pattern - "bag of worms".

Ependymoma

Microscopy

Features:

• Cells have a "tadpole-like" morphology.
  • May also be described as ice cream cone-shaped.
• Rosettes - cells arranged in a pseudoglandular fashion.
• "Nucleus free zones" - cells arranged around a blood vessel (pseudorosettes) - vessel not seen, only cytoplasm of tumour cells.
  • The nucleus free zone is composed of tumour cell cytoplasm that is adjacent to an unseen blood vessel.
• Nuclear feature monotonous, i.e. "boring".

DDx:

• Subependymoma.

Choroid plexus papilloma

Microscopy

Features:

• Papillae.
• Psammoma bodies.

Image:

• Choroid plexus papilloma (WC).

Chordoma

• Location: usually sacrum or clivus.

Microscopic

Features:

• Architecture: islands of cells surrounded by fibrous tissue.
  • Also described as "lobulated" architecture; may not be apparent.
• Myxoid background - grey extracellular material, variable amount present.
• Mixed cell population:
  1. Abundant eosinophilic cytoplasm.
  2. Physaliphorous cells or bubble cells - key feature.
     • Have a very large clear bubble with a sharp border; bubble does not compress nucleus - nucleus may be in bubble.

Image(s):

• Chordoma - crappy quality image (surgical-pathology.com).

IHC

Features:

• S100 +ve.
• CK +ve.
• Brachyury +ve.
  • Protein important for axial development, affects notochord development.
  • Brachyury literally means short tail.

External links

• Neuropathology - neuropathologyweb.org.
• Neuropathology Mini-Course - pathology.vcu.edu.