Soft tissue tumours- Peripheral nerves Flashcards Preview

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Flashcards in Soft tissue tumours- Peripheral nerves Deck (25):

What is a Neurilemoma?

  • A Benign Encapsulated Tumour composed of Schwann cells
    • tumour is well encapsulated on Surface of Peripheral nerve
    • AKA Schwannoma
  • Peak incidence 30/ 60 years
  • M=F
  • often Flexor surfaces of head/neck
  • larger lesion maybe in Pelvis
  • can effect motor & sensory nerves
  • Genetics
    • often assoc w mutations affecting NF2 gene
  • Malignant change rare

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What is the presentatino of a pt with  Neurilemoma?

  • Usually asymptomatic
  • may have Parathesia in the distribution of the peripheral n


  • Tinels sign positive w the nerve affected


What is seen on imaging of  Neurilemoma?

  • MRI
    • low intensity = dark on T1
    • high intensity = bright on T2
    • diffuse enhancement w gadolinium
    • may show Shoe string sign
    • difficult to differentiate from neurofibroma

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What is seen on histology of  Neurilemoma?

  • Macro= Nerve encapsulated in nerve sheath
  • Micro
    • Antoni A structure= spindel cell battle formation
    • Antoni B- areas w less cellularity w loosely arranged cells
    • Verocay Bodies
      • pathognomonic
      • 2 rows of aligned nuclei in a palisading formation
      • strongly stains for S100 antibody

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What is the tx of neurliemoma?

Non operative

  • Observation
    • asymptomatic lesions


  • Marginal excision
    • symptoms affecting quality of life
    • nerve function may be preserved by careful dissection, excising the lesion parallel to nerve fascicles so the lesion may be extruded
    • small risk of sensory deficit
    • reoccurance is rare


Describe and name some common neuromas?

  • a growth /tumour of nerve cells
  • Often Benign
  • Morton's neuroma
    • interdigital neuroma
  • recurrent neuroma


What is Malignant peripheral nerve sheath tumour?

  • Arises from peripheral nerve or neurofibroma
  • aka neurofibrosarcoma, malignant schwannoma
  • 30-55 yrs solitary neurofibromas
  • 20-40 yrs for neurofibromatosis type 1 ( NF-1)
  • Genetics
    • most associated with NF-1 :  4% incidence
  • Prognosis
    • survival solitary lesion 75% ( 5yr survival)
    • Survival assoc with NF-1 is 30% ( 5 yr survival)

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What is the presentation of malignant peripheral nerve sheath tumour?

  • Soft tissue mass
  • most arise form large nerves ( sciatic. brachial plexus)
  • Motor and sensory deficit of affected nerves


 imaging like for malignant perpherial nerve sheath tumours


  • radiography
    • normal or non specific soft tissue mass
  • MRI
    • low intensity on T1 weight images
    • high intensity on T2 weight images
    • serial MRI- enlargement of previous benign nerve sheath lesions suggesting malignant transformation
  • Bone Scan
    • Mildly positive

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Describe the histology in malignant peripheral nerve sheath tumours?


  • Spindle cells with wavy nuclei resembling fibrosarcoma
  • immunostaining
    • positive S100
    • Keratin staining is negative

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What is the tx for malignant  peripheral nerve sheath tumour?


  • Operative
    • Wide surgical resection and radiation
      • most pts
      • tx as high grade sarcoma
      • wide resection should include entire affected nerve
      • neoadjuvant radiation
      • chemotherapy not useful


What is a neurofibroma?


  • Benign nerve sheath tumours with multiple cell types
    • fibroblasts ( predominant cells)- Neurofibromas
    • Nonmyelinating Schwann cells= Schwannomas
      • cell of origin, arises from cell with bialletic inactivation of NF1 tumour-suppressor gene of protein neurofibrin
      • loss of expression of protein neurofibromin
        • neurofibromin negatively regulates RAS- mediated pathway
        • loss of neurofibromin -> increase Ras activity
        • effects ras- dependent MAPK activity which is essential for osteoclast function & survival
      • Rapid Hyperplasia of nonmyelinating Schwann cells into Neurofibromas after NF1 inactivation

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What the is location and age group of sporadic Neurofibromas?


  • peripheral PNS tumours of the extremities
  • Age group 20-40 yrs


What is the location and age group of neurofibromatosis NF1?



  • Tendency to be found near spinal cord/brain and uncommon locations ( parotid glands, tongue)
  • Inheritance AD 17q11.2
  • Age


Decribe the subtypes of neurofibromas?


  • Dermal
    • arise from single peripheral nerve= centrally entering and exiting nerve
    • Fusiform swelling of nerve
    • they lack a capsule and cannot be separated from normal nerve fibres
    • 90% sporadic. 10% arise from NF1
    • onset At puberty
    • Don't become malignant
  • Plexiform
    • arise from multiple nerve bundles
    • 'bag of worms ' ( tortuous enlargment of nerves)
    • Pathognomic of NF-1
    • Onset early childhood
    • 10% -> malignant= Malignant Peripheral Nerve Sheath Tumour, 10-25 % lifetime risk, assoc with loss of expression of CDKN2A or TP53 genes in non myelinating Schwann cells


Describe the subtypes of Schwann cells?


  • Myelinating
    • covers large diameter PNS axons with myelin
  • Nonmyelinating
    • covers small diameter PNS axons with cytoplastic processes
    • responsible for Neurofibromatosis


Describe the presentation of Neurofibromas?

  • Asymptomatic
  • stinging, itching, pain , disfiguration


  • reduced sensation
  • Cutaneous lesions
    • can button hole thru skin defect using finger pressure
  • Signs of NF 2 0f 7 criteria
    • 2 or more neurofibromas, or 1 plexiform neurofibromas
    • axillary or groin freckling ( crowe's sign)
    • 6 or more California cafe au lait spots- seepic
      • 5mm in prepubertal
      • >15mm in post pubertal
    • Spheniod wing dysplasia or thinning of long bone cortex
    • 2 or ore Lisch nodules ( iris hamartomas)
    • optic glioma
    • 1st degree relative with NF-1

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What is seen of neurofibromas on imaging?

  • MRI
    • differentiate Schwannoma from neurofibroma
      • shcwannoma are ECCENTRIC around nerves
      • Solitary neurofibroma are found CENTRAL to the nerve fibres
    • Target sign- loss of high signal intensity peripherally and low signal centrally

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What is seen on histology of neurofibromas?


  • Predominant fibroblasts
  • elonagted nuclei
  • mixed schwann cells, mast cells , lymphocytes
  • Stroma- rich wire like collagen fibre network


What is the tx of neurofibromas?


  • Non operative
    • Observe
      • if asymptomatic
  • Operative
    • Surgical Excision
      • if symptomatic
      • may require Nerve Grafting


What is a neuroblastoma?


  •  Malignant tumour which develops from sympathetic neural tissue ( neoplastic trasnformation of neural- crest cells)
  • Most common solid tumour of childhood
  • most arise in adrenal gland or  near the spinal cord
  • occurs in 1, 100,00 children
  • > Males
  • majority occur
  • Mets to bone common - poor prognostic sign
  • prognosis= most children cured
    • in v young spontaneous regression of tumour known to occur

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What is the presentation of a neuroblastoma?


  • Fever, Malaise, weight loss, diarhoea
  • Abdominal mass
  • Adrenal mass-> tachycardia


  • abdo mass/ hepatosplenomegaly
  • biopsy - opne vs needle to make dx

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What is seen on imaging of neuroblastoma?



  • Bony lesions in case of mets
    • Permative & lytic lesions
    • anywhere in skeleton


  • Chest/abdo/pelvis-extent of disease


  • delinate anatomical structures

Bone scan

  • extent of mets

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What is seen on histology of neuroblastoma?


  • Small round blue cells-> rosette pattern
    • other dx of small round blue cells
      • Ewing's sarcoma
      • Rhabomyosarcoma
      • Non hogkins lymphoma

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What is the  tx of neuroblastoma?


Non operative

  • Observation
    • V young infants w low risk tumours
    • a number can spontaneously regress
  • Chemotherapy and Stem cell transplant
    • Children w high grade/ mets disease not amenable to surgery
    • Cisplatin, ifosfamide then stem cell transplant


  • Surgical excision
    • Local wide surgical excision
  • Chemo, Stem cell transplant, & surgical resection
    • high grade tumours near important NV structures that cannot be escised with wide margins