Soft tissue tumours- Peripheral nerves Flashcards
Neurilemoma- Schwanoma Neuroma MPNST Neurofibroma Neuroblastoma
1
Q
What is a Neurilemoma?
A
-
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
2
Q
What is the presentatino of a pt with Neurilemoma?
A
- Usually asymptomatic
- may have Parathesia in the distribution of the peripheral n
)/E
- Tinels sign positive w the nerve affected
3
Q
What is seen on imaging of Neurilemoma?
A
- 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
4
Q
What is seen on histology of Neurilemoma?
A
- 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
5
Q
What is the tx of neurliemoma?
A
Non operative
-
Observation
- asymptomatic lesions
Surgery
-
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
6
Q
Describe and name some common neuromas?
A
- a growth /tumour of nerve cells
- Often Benign
- Morton’s neuroma
- interdigital neuroma
- recurrent neuroma
7
Q
What is Malignant peripheral nerve sheath tumour?
A
- 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)
8
Q
What is the presentation of malignant peripheral nerve sheath tumour?
A
- Soft tissue mass
- most arise form large nerves ( sciatic. brachial plexus)
- Motor and sensory deficit of affected nerves
9
Q
imaging like for malignant perpherial nerve sheath tumours
A
- 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
10
Q
Describe the histology in malignant peripheral nerve sheath tumours?
A
- Spindle cells with wavy nuclei resembling fibrosarcoma
- immunostaining
- positive S100
- Keratin staining is negative
11
Q
What is the tx for malignant peripheral nerve sheath tumour?
A
- 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
-
Wide surgical resection and radiation
12
Q
What is a neurofibroma?
A
- 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
13
Q
What the is location and age group of sporadic Neurofibromas?
A
- peripheral PNS tumours of the extremities
- Age group 20-40 yrs
14
Q
What is the location and age group of neurofibromatosis NF1?
A
- Tendency to be found near spinal cord/brain and uncommon locations ( parotid glands, tongue)
- Inheritance AD 17q11.2
- Age
15
Q
Decribe the subtypes of neurofibromas?
A
-
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
17
Q
Describe the presentation of Neurofibromas?
A
- Asymptomatic
- stinging, itching, pain , disfiguration
O/E
- 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
18
Q
What is seen of neurofibromas on imaging?
A
-
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
- differentiate Schwannoma from neurofibroma
21
Q
What is a neuroblastoma?
A
- 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
22
Q
What is the presentation of a neuroblastoma?
A
- Fever, Malaise, weight loss, diarhoea
- Abdominal mass
- Adrenal mass-> tachycardia
O/E
- abdo mass/ hepatosplenomegaly
- biopsy - opne vs needle to make dx
23
Q
What is seen on imaging of neuroblastoma?
A
Xray
- Bony lesions in case of mets
- Permative & lytic lesions
- anywhere in skeleton
CT
- Chest/abdo/pelvis-extent of disease
MRI
- delinate anatomical structures
Bone scan
- extent of mets
24
Q
What is seen on histology of neuroblastoma?
A
- Small round blue cells-> rosette pattern
- other dx of small round blue cells
- Ewing’s sarcoma
- Rhabomyosarcoma
- Non hogkins lymphoma
*
- other dx of small round blue cells
