Tumours Of The Orbit Flashcards
What do they need to know for tumours of the orbit?
- Distribution of pathology
- Possible diagnosis based on imaging
- Relationship to normal structures - ON
- Definition of bony anatomy - ON
- Definition of bony anatomy
When may MR be useful?
Looking for intracranial disease spread - direct or distant peripheral better definition of pathology and relationship to/arising from ON vascular masses
What are neoplasms?
Arise from optic nerve sheath complex which consist of nerve, a white matter tract and surrounding sheath which is an extension of dura
What are optic nerve sheath complex?
- Meningioma
2. Glioma
What is conal/intraconal?
- Inside the muscle cone
- A lot of pathology can straddle different compartments
- Lymphoma
- Peripheral nerve sheath tumour
- Melanoma
What are examples of extraconal?
- Lacrimal
- Peripheral nerve sheath tumour
- Rhabdomysarcoma
- Haemangiopericytoma
- Metastasis
What is ON glioma 1?
- Tumour arising from the optic nerve
- Most common one is optic nerve glioma
- Optic nerve glioma is often seen in children
- Childhood form is usually a low grade - non aggressive aplastic astrocytoma
What is ON glioma 1?
- 60% of all primary ON tumours
- 4% of all orbital tumours
- Peak age 2-8 years
- Strong association with NF1 - 25%
- If bilateral then pathgnomic of NF1
- 2 distinct forms - childhood and adult
- Childhood form - more common; may follow indolent course - even spontaneous regression
- Histologically similar time pilocytic astrocytoma
What is ON glioma imaging?
- NF1 May see other intracranial lesions - cerebellum, basal ganglia
- Spectrum - thickening of ON due to arachnoid hyperplasia through to fusiform or globular mass
- Cystic change common
- Optical canal widening
- MR - T1 is oi tends to brain; T2 hyper intense
- Variable enhancement - often less than ONSM
What is radiological differential of ON glioma?
- ONS meningioma
- Schwannoma
- Lymphoma
- Metastasis
- Optic neuritis
- Infectious/granulonateous neuritis
- Idiopathic orbital inflammation
What is ON sheath meningioma?
- 10-33% of orbital tumours
- Meningothelial cells of arachnoid or extension from intracranial lesion
- Occasionally - ectopic arachnoid cells in muscle cone or orbital wall
- Clinical triad - progressive visual loss, optic atrophy and opticociliary shing vessels
- Middle aged females
- Express female hormone receptors
- Childhood form more aggressive and associated with NFII
- Bilateral tumours may/may not be associated with NF
What do patient notice subtle changes in their vision with?
- Menstruation
2. Pregnant
What shouldn’t you put patients with meningioma on?
Hormone replacement therapy
What can meningioma be associated with?
Neurofibromatosis type 2
What are the shape of tumours?
Variable shape
Long and tubular centric
What is exposure ceroscopy?
When the globe comes forward you cannot close your eyelids
You can get problems with lubrications of the globe
What is meningioma?
Low grade - slow growing
What is ON sheath meningioma:imaging?
- CT - sheath calcification almost pathognomic
- Variable shape - tubular, fusiform or globoid
- enhancement avid
- Encased ON attenuated/ atrophic
- Pneumosinus dilitans
- Hyperostosis of anterior clinoid process; optic canal narrow or widened
- Anterior capping cyst
- MR - often Isointense to brain on T1 and T2; May be T1 hypointense and T2 hyper intense
What is ON sheath meningioma radiological differential?
- Glioma
- Cavernous haemangioma
- Schwannoma
- Haemangiopericytoma/solitary fibrous tumour
- Lymphoma
- Metastases
- Idiopathic orbital inflammation
- Optic neuritis
- Sarcoidosis
What is Lymphoma?
Insidious presentation - painless propria is and decreased motility (not greatly impaired due to small amount of collagen)
Age 50-70 years - rare in children
Predilection for lacrimal gland - smooth superotemporal palpable pink mass
Superior/anterior orbit, conjunctiva and eyelids frequently involved
75% unilateral -bilateral older age group
What are patterns of involvement for lymphoma ?
- Anterior preseptal/postseptal and superior involvement
- Lacrimal gland - orbital + often palpebral components; bony remodelling; bulkier than IOI
- Retrobulbar involvement; well circumscribed mass or infiltrative replacing fat; moulds around existing orbital structures - no identation of globe regardless of size
- Extension of lymphomarous lesions e.g. from sinonasal cavity
What does lymphoma mass affect?
Inferior rectus
What is lymphoma ?
A cellular tumour - it enhances a lot
What is lymphoma imaging?
- 75% homogenous on CT
- Bone destruction rare
- Infiltration and thickening of muscles less common than in idiopathic orbital inflammation
- MR: isointense to muscle on T1; T2 signal variable
- hyperintense to fat and isointense to brain (IOI isointense to fat on T2) - Enhancement less than IOI
What is radiological differential?
- Reactive lymphoid hyperplasia
- Metastases
- Inflammatory - idiopathic, sarcoid, Wegner
- Infection
- Unusual
What is Leukaemia?
- Orbital involvement - part of systemic disease
- In children mainly with AML and adults CLL
- Imaging: intraocular and orbital haemorrhage- low platelet
- Leukaemic infiltration of uvea, choroid, Regina and ON
- Infiltration of soft tissues; mass like or diffuse, usually fat
- AML - granulocytic sarcoma (chloroma) with bone destruction
- AML in absence of peripheral blood involvement; either lateral wall extending to temporal fossa or medial to anterior cranial fossa - presents at approximately age 7
What are lacrimal tumours?
- Lacrimal lesions
- epithelial - mainly neoplastic
- 40-50% of lacrimal masses
- non epithelial - congenital / inflammatory and some neoplasms (lymphoma) - Most common lacrimal tumours - benign mixed pleomorphic Adenoma and adenocystic Carcinoma
What is lacrimal tumours: adenocystic carcinoma ?
- 2nd most common epithelial lacrimal tumour (29%)
- 4.8% of primary orbital neoplasms
- Younger age 4th decade
- Better prognosis in young patients than adults
- Firm hard mass; rapid growth, Peru neural and vascular invasion
- Rounded configuration distorting globe and orbitals content
- Involvement of surrounding bone
- Calcification more common
What is peripheral nerve tumours?
- PNT - 4% of orbital tumours
- 2% plexiform neurofibromas, 1% isolated neurofibromas, 1% schwannoma
- Sensory neves > motor
- Slowly progressive proptosis & pain; ocular motility preserves
- Malignant transformation is rare - more common in neurofibromas
What is plexiform?
Pathognomonic of NF with orbital involvement
What is neurofibromas?
Infancy/childhood - initially eyelid mass localised to lateral 1/3
Adolescences spread to forehead, temple and orbit
Diffuse: similar to plexiform, less likely to be associated with NF
Circumscribed: slow growing, more common in superior quadrant
Presents 3rd-5th decade
What is imaging of neurofibromas?
- Childhood forms associated with orbital enlargement
- Look for features on NF with plexiform types-sphenoid wing dysplasia, enlarged glove
- Infiltrative appearance involving soft tissues heterogenous hypointense T1 and hyper intense T2 signal
- variable enhancement; may be avid as vascular
What are schwannomas?
- Schwannoma clinically indistinguishable from circumscribed neurofibromas
- Arise from sensory nerves
- Located near orbital apex
- Solitary neurofibromas/ schwannomas - well circumscribed oval/ fusiform mass
- Isointense to muscle and brain on T1
- Hyperintense on T2
- Heterogenous enhancement
What is solitary fibrous tumour?
- Rare orbital vascular tumour
- Arises from Pericytes of Zimmerman, around capillaries and post capillary venues
- Histology varies from benign to malignant
- Propensity for late recurrence - several decades
- Age - infancy to elderly; most in early 40s
- No gender predilection
What is Rhabdomyosarcoma 1?
- Most common soft tissue childhood malignancy (50% of soft tissue sarcoma)
- Most common primary orbital childhood tumour - rare
- Derived from undifferentiated mesenchyme of orbital soft tissue
- Most present < 16 years; average age at diagnosis 7-8 years
- May be present at birth
- Rapid proptosis with globe displacement
What is Rhabdomyosarcoma 2?
- Unilateral and unifocal; anywhere in orbit, though most superior and medial
- Epicentre mainly extraconal in 60%, intraconal in 40% both 47%
- Chromosomal translocation between 2 & 13, and abnormality of Chr 11
- Embryonal is most common type
- Alveolar type is 2nd most common; older children inferior orbit, more aggressive
