Schwannoma

Clinical features

  • Unusual in children (5% of the neurogenic tumours)
  • Most sporadic- V and VIII cranial nerves
  • Bilateral VIII cranial nerve- Neurofibromatosis type 2
  • Head , neck, extremities (flexor zones)
  • Slow growing and painless

 

Fig 34 – Schwannoma –Cohesive tissue fragments. Fragments of uniform spindle shaped cells in a moderate collagenous matrix (H&E)
Fig 35 – Schwannoma - Spindle cells with ovoid, comma or wavy nuclei and nuclear palisading (Verocay Bodies).Bland population and absence of necrosis (H&E)
Fig 36 - Schwannoma – Some elongated wavy nuclei (Giemsa)

 

 

  • Low sensitivity
  • Pain during aspiration
  • Cohesive cells in tissue fragments (helpful criteria of low grade/benign nerve sheath tumours)
  • Nuclear palisading (Verocay bodies)- (helpful pattern)
  • Spindle cells with ovoid, comma or wavy nuclei
  • Intranuclear cytoplasmic inclusions
  • Fibrillary cytoplasm
  • Anisokariosis can be present-Ancient Schwannoma
  • No mitosis
  • Melanotic pigment can be present in HMB45 positive cells

 

Immunocytochemistry

  • Vimentin: Positive
  • S100 protein: Positive
  • Leu7: Positive
  • GFAP: Positive (occasional)

 

Differential Diagnosis

  • Neurofibroma
    • Nuclear features are in most of the cases indistinguishable
    • In these kind of lesions the main point of cytological diagnosis is that of a benign neurogenic tumour
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