Peripheral nerve sheath tumours

Peripheral nerve sheath tumours, abbreviated PNSTs, are common in neuropathology and occasionally show-up elsewhere. A very common PNST is the schwannoma.

Classification

A classification:

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

Schwannoma

General

• A common neuropathology tumour that occasionally shows-up elsewhere.
• Tumour of tissue surrounding a nerve.
  • Axons adjacent to the tumour are normal... but may be compressed.
• May be a part of neurofibromatosis type 2.

Microscopic

Features:

• Antoni tissue (type A and type B).
• Verocay bodies - paucinuclear area surrounded by nuclei.
• In the GI tract: classically have a peripheral lymphoid cuff.

Notes:

• Tumour does not smear well.

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).

Traumatic neuroma

General

• Consequence of trauma -- diagnosis requires history of trauma.

Microscopic

Features:

• Nerve with adjacent small organized micro-fascicles in collagen - as seen in regeneration.

Neurofibroma

General

• May be a part of neurofibromatosis 1.
• Composed of Schwann cells, axons, fibrous material.

Microscopic

Features:

• Plexiform growth pattern - "bag of worms".

Image:

• Neurofibroma - low mag. (WC).
• Neurofibroma - high mag. (WC).
• Neurofibroma - high mag. (WC).

Malignant peripheral nerve sheath tumours

General

• Malignant - as the name implies.

Microscopic

Features:

• Mitoses.

Image(s):

• MPNST (sarctrials.org).

See also

• Neuropathology.
• Gastrointestinal pathology.