Orbit

Question 1

(Ped) 24. Regarding MR features of rhabdomyosarcoma:

A. Hyperintense to muscle on T1

B. Hypointense to muscle on T2

C. Homogenous enhancement T1 post-contrast

D. Well-defined margins

E. High SI on Short TI Inversion Recovery (STIR)

Answer 1

E. High SI on Short TI Inversion Recovery (STIR)

Other features include local oedema, extension and destruction. Usually isointense to muscle on T1, similar or hyperintense to muscle on T2 and with poorly defined margins and heterogeneous contrast enhancement.

Question 2

26. A 20-year-old woman has a right-sided proptosis, chemosis and bruit over the orbit. On MRI she is found to have dense enhancement of the right-sided extra-occular muscles with dilatation of the right cavernous sinus and periorbital soft tissues. Angiography reveals abnormal early opacification of a dilated left cavernous sinus and superior ophthalmic vein. Which is the most likely diagnosis?

A. Carotid-cavernous fistula

B. Thyroid eye disease

C. Orbital pseudotumour

D. Retro-orbital metastases

E. Optic nerve plexiform neurofibroma

Answer 2

A. Carotid-cavernous fistula

MR angiography shows reversal of flow through the Superior Ophthalmic Vein (SOV), rapid progress of proptosis, visual loss or raised intracranial pressure requiring emergency treatment.

Question 3

27. A 60-year-old woman with mild proptosis undergoes a CT which shows enlargement of the bellies of the medial, and to a lesser extent, lateral rectus muscle. Tendons appear normal. What is the likely diagnosis?

A. Idiopathic orbital myositis

B. Carotid cavernous fistulae

C. Retro-orbital metastases

D. Graves ophthalmopathy

E. Plexiform neurofibroma of optic nerve

Answer 3

D. Graves ophthalmopathy

Sparing of muscle tendons is typical. Most cases are bilateral

Question 4

39. Which feature indicates orbital meningioma compared with optic nerve glioma?

A. Straight optic nerve

B. Well-defined margins

C. Rarely calcifies

D. Absence of hyperostosis

E. Widened optic canal

Answer 4

A. Straight optic nerve

Other features of meningioma include calcification, homogenous enhancement and hyperostosis

Question 5

47. Which of the following is an extraconal extraorbital lesion, rather than an extraconal intraorbital lesion?

A. Squamous cell carcinoma of the sinus

B. Teratoma

C. Dermoid cyst

D. Capillary haemangioma

E. Lymphangioma

Answer 5

A. Squamous cell carcinoma of the sinus

Other causes are lymphoma, adenocarcinoma, adenoid cystic carcinoma, mucoceles and paranasal sinusitis.

Question 6

(Ped) 12) A 2-year-old boy presents to his general practitioner with decreased visual acuity and pain in the left eye. Examination reveals a white light reflex (leukocoria) in the affected eye. Subsequent CT shows a retrolental, solid, lobulated, hyperdense mass with punctate calcification. The vitreous humour is abnormally dense. What is the most likely diagnosis?

a. orbital pseudoglioma

b. retrolental fibroplasia

c. retinoblastoma

d. Coats’ disease

e. persistent hyperplastic primary vitreous

Answer 6

c. retinoblastoma

Retinoblastoma is a highly malignant primary ocular tumour of childhood occurring in sporadic and heritable form and arising from primitive photoreceptor cells of the retina (in the group of primitive neuroectodermal tumours). It is the most serious intraocular process in a child, and calcification in a paediatric orbit must be considered to represent retinoblastoma until proved otherwise.

Once tumour extends beyond the orbit, mortality rate is virtually 100%. Heritable forms are often multifocal in a single orbit or bilateral.

Trilateral retinoblastoma is bilateral orbital tumours and associated pineoblastoma.

Question 7

30) A patient presents with diplopia and is found to have unilateral restricted eye movements. On MRI, the extraocular muscles of the same eye are seen to be enlarged and oedematous. Which of the following additional features favours carotid–cavernous sinus fistula as Dx, over Graves’ disease, lymphoma or orbital pseudotumour?

a. distal tapering of the swollen extraocular muscles

b. stranding in the orbital fat

c. extraocular muscles isointense to fat on T2W images

d. dilated superior ophthalmic vein

e. extraocular muscle swelling involving the tendons

Answer 7

d. dilated superior ophthalmic vein

Carotid–cavernous sinus fistula can be caused by penetrating injury, base of skull fracture or rupture of an intracavernous internal carotid artery aneurysm. Drainage from the affected cavernous sinus is via the superior ophthalmic vein, contralateral cavernous sinus, petrosal sinus and, rarely, cortical veins. Pulsatile exophthalmos and orbital bruit are evident, as are chemosis, conjunctival oedema and increased intraocular pressure. On imaging, the cavernous sinus may be enlarged, and can cause erosion of the sella and enlargement of the superior orbital fissure.

Regarding the differentials for extraocular muscle swelling, Graves’ disease typically spares muscle attachments.

Inflammatory orbital pseudotumour affects tendons while also causing orbital fat stranding.

Question 8

87) A 38-year-old male presents with a history of recent head injury and unilateral, painful, pulsatile exophthalmos with reduced visual acuity. CT shows swelling of the extraocular muscles with dilatation of the superior ophthalmic vein and cavernous sinus on the ipsilateral side, both of which enhance avidly. What is the most likely diagnosis?

a. ophthalmic varix

b. arteriovenous malformation

c. lymphangioma

d. carotid–cavernous fistula

e. pseudotumour of orbit

Answer 8

d. carotid–cavernous fistula

Carotid–cavernous sinus fistula may occur spontaneously (secondary to aneurysm rupture, dural sinus thrombosis or atherosclerosis) or after trauma/surgery.

It presents with a classic triad of pulsatile exophthalmos, conjunctival chemosis and auscultatory bruit. However, reduction in visual acuity may be the only sign.

Secondary findings such as proptosis, congestive extraocular muscle enlargement, and distension with enhancement of the superior ophthalmic vein and cavernous sinus are usually identified on routine CTor MRI.

However, catheter angiography is usually required for lesion classification and treatment planning prior to embolization.

Drainage may also occur into the contralateral cavernous sinus, resulting in dilatation and enhancement.

Ophthalmic varices present with intermittent exophthalmos related to straining, with dilatation of superior and/or inferior ophthalmic veins, which may thrombose.

Orbital pseudotumour is an idiopathic inflammatory condition affecting all orbital contents, but vascular dilatation is not a feature.

Question 9

1 A patient presents with a slowly progressive loss of vision. Enlargement of the optic nerve is seen on MR imaging. Which of the following features would be more in keeping with an optic nerve glioma, rather than an optic nerve sheath meningioma?

(a) Unilateral lesion

(b) Calcification

(c) Kinking of the optic nerve

(d) Hyperostosis

(e) Linear bands of enhancement following i.v. gadolinium

Answer 9

(c) Kinking of the optic nerve

Optic nerve glioma is the most common cause of diffuse optic nerve enlargement.

NF-1 is present in 25%.

Kinking and buckling of the optic nerve is common.

Calcification, hyperostosis, and the ‘tramtrack’ sign (linear bands of enhancement) are features more typical of meningioma.

Question 10

2 A female child has problems with upward gaze. A CT head reveals a densely-enhancing pineal mass with ‘exploded calcifications’. There is CSF seeding. Which other tumour type is this condition associated with?

(a) Retinoblastoma

(b) Teratoma

(c) Meningioma

(d) Pilocytic astrocytoma

(e) Neurofibroma

Answer 10

(a) Retinoblastoma

Pinealoblastomas are ass with bilat retinoblastomas (combination producing called ‘trilateral retinoblastoma’)

Question 11

33 A 55 year old has unilateral visual loss. An ocular US demonstrates an echogenic, posterior segment mass of a ‘cottage loaf’ appearance. Doppler imaging reveals blood flow within. What is the most likely diagnosis?

(a) Choroidal melanoma

(b) Metastasis

(c) Retinoblastoma

(d) Vitreous haemorrhage

(e) Vitreo-retinal traction

Answer 11

(a) Choroidal melanoma

The ‘cottage loaf’ appearance derives from the tumour breaking through the basal lamina of the choroid, and is said to be specific for choroidal melanoma.

Question 12

46 A middle aged lady presents with bilateral proptosis. There is eyelid retraction and lid lag on downgaze. CT demonstrates bilateral enlargement of the extraoccular muscles with sparing of the tendons. Given the most likely disease process, which of the following would one expect to be affected last?

(a) Superior rectus

(b) Inferior rectus

(c) Medial rectus

(d) Lateral rectus

(e) Oblique muscles

Answer 12

(e) Oblique muscles

The patient is suffefiing from thyroid-associated orbitopathy. The muscles are affected in the following order: inferior, medial, superior, lateral, oblique muscles (mnemonic ‘‘l’M SLO”).

Question 13

3 A neonate presents with unilateral leukocoria and microphthalmia. An US reveals a hyperechoic band within the globe. CT demonstrates a hyperdense vitreous, fluid-fluid levels and ail absence of calcification. No focal mass is seen. What is the most likely diagnosis?

(a) Coat’s disease

(b) Persistent hyperplastic primary vitreous

(c) Retinal dysplasia

(d) Retinoblastoma

(e) Toxocariasis

Answer 13

(b) Persistent hyperplastic primary vitreous

Persistent hyperplastic primary vitreous is caused by the persistence of the embryonic hyaloid vascular system. Its features are microphthalmia, a vitreous body remnant of the hyaloid artery, retinal detachment andleukocoria, a hyperdense vitreous from previous haemorrhage, fluidfluid levels from the degradation of haemorrhage, and an absence of calcification.

Question 14

28 Thickening of the extra-ocular muscles is seen on MR imaging. What features would support the diagnosis of pseudotumour rather than thyroid ophthalmopathy?

(a) Bilaterality

(b) Ocular muscle tendon involvement

(c) Atrophy of the lacrimal gland

(d) Minimal response to steroids

(e) Painless proptosis

Answer 14

(b) Ocular muscle tendon involvement

Orbital pseudotumour tends to: be unilateral (85%), involve the tendons, cause stranding of the intra-orbital fat, enlarge the lacrimal gland, be painful, and have a good response to steroids.

Question 15

75 You are asked to review an MRI brain, and note that there is a focal abnormality of the left globe. There is a localized outpouching of the vitreous near the site of the optic nerve attachment. What is likely diagnosis?

(a) Normal variant

(b) Phthisis Bulbi

(c) Buphthalmos

(d) Staphyloma

(e) Coloboma

Answer 15

(e) Coloboma

A coloboma represents incomplete closure of the foetal choroidal fissure, affecting the eyelid, retina, choroid and iris. It can be associated with microphthalmos and the morning glory anomaly (where the optic disk is enlarged and elevated). It is commonly bilateral

Question 16

6. A 50 year old woman presents with visual loss. Examination reveals retinal detachment and an ocular lesion. On MRI, the lesion is hyperintense on T1 and hypointense on T2 relative to the vitreous. The lesion enhances post-gadolinium injection. The most likely diagnosis is:

a. Metastases from breast cancer

b. Metastases from lung cancer

c. Choroidal haemangioma

d. Malignant melanoma

e. Vitreous lymphoma

Answer 16

6.d. Malignant melanoma

This is the most common primary intraocular neoplasm in adult Caucasians. The typical age range is 50–70 years old. They are almost always unilateral and located in the choroid, although ciliary body and iris melanomas are not uncommon. Presentation can be with retinal detachment, vitreous haemorrhage, astigmatism or glaucoma. MRI shows a sharply circumscribed hyperintense lesion on T1, due to the paramagnetic properties of melanin, and hypointense relative to the vitreous body

Question 17

7. A 35 year old previously well female consults an ophthalmologist with a history of progressive loss of visual acuity over several months. Retinal examination reveals papilloedema. Unenhanced CT shows tubular thickening of the optic nerve associated with dense calcifications. Post-contrast injection shows a non-enhancing optic nerve surrounded by a markedly enhancing soft-tissue mass. The remainder of the brain is normal. The most likely diagnosis is:

a. Optic nerve glioma

b. Perioptic meningioma

c. Sarcoidosis

d. Lymphoma

e. Multiple sclerosis

Answer 17

7.b. Perioptic meningioma

These tumours account for less than 2% of all intracranial meningiomas.

They occur within the third to fifth decades and are more common in females.

They are also associated with neurofibromatosis type 2.

They typically present with progressive loss of visual acuity over several months due to optic atrophy.

They are usually tubular in appearance although fusiform and excrescentic thickening of the optic nerve also exist.

Tumour enhancement around a non-enhancing optic nerve (tram-track sign) and calcification are highly suggestive of meningioma

Question 18

11. A middle-aged female presents with unilateral proptosis. CT of the orbits reveals an intraconal mass with involvement of the lateral rectus muscle to its point of tendinous insertion. The lesion enhances post-contrast injection. MRI shows a mass which is hypointense to fat on T2. What is the most likely diagnosis?

a. Thyroid opthalmopathy

b. Lymphoma

c. Cavernous haemangioma

d. Capillary haemangioma

e. Pseudotumour

Answer 18

11. e. Pseudotumour

Pseudotumour is the commonest cause of an intra-orbital mass lesion in adults.

It is an idiopathic inflammatory condition and about 10% of cases occur in association with autoimmune conditions such as retroperitoneal fibrosis.

It usually presents with unilateral painful opthalmoplegia. It can be acute (more common) or chronic.

The former has a more favourable prognosis as it is responsive to steroids.

In contrast, the chronic type frequently requires chemotherapy and radiotherapy.

On MRI, pseudotumour is hypointense to fat on T2, whereas true tumours are hyperintense.

Grave’s disease is the most common cause of uni/bilateral proptosis in adults (_85% bilateral, 15% unilateral).

However, involvement of extra-ocular muscles tends to maximally affect the midportion with relative sparing of the tendinous insertions. This gives rise to the so-called ‘Coke-bottle’ sign.

Question 19

(Ped) 15. An 11 year old boy undergoes investigation for a mass in his right orbit. CT shows a hypodense mass located in the upper temporal quadrant. The Hounsfield units are positive throughout the lesion. There is no calcification and the lesion does not enhance. There is adjacent scalloping of the lateral orbital wall. On MRI, the lesion is hypointense on T1 and hyperintense on T2, FLAIR and diffusion-weighted imaging. What is the most likely diagnosis?

a. Orbital teratoma

b. Orbital pseudotumour

c. Conjunctival choristoma

d. Dermoid cyst

e. Epidermoid cyst

Answer 19

15. e. Epidermoid cyst

Both epidermoid and dermoid cysts appear as unenhanced, well-circumscribed, low-density masses. Both can cause scalloping and sclerosis and even destruction of the adjacent bone. Epidermoids do not calcify and do not contain fat (negative Hounsfield units). The presence of calcification and/or fat is characteristic of dermoid cysts. Dermoids and epidermoids have low signal on T1 (unless the former contains fat) and high signal on T2, FLAIR and diffusion-weighted imaging. Both may be found in several 15. e. Epidermoid cyst Both epidermoid and dermoid cysts appear as unenhanced, well-circumscribed, low-density masses. Both can cause scalloping and sclerosis and even destruction of the adjacent bone. Epidermoids do not calcify and do not contain fat (negative Hounsfield units). The presence of calcification and/or fat is characteristic of dermoid cysts. Dermoids and epidermoids have low signal on T1 (unless the former contains fat) and high signal on T2, FLAIR and diffusion-weighted imaging. Both may be found in several

Question 20

@# 33. A 65 year old woman is investigated for enophthalmos and headache. She is cachetic, anaemic and you suspect a metastatic process. CT head demonstrates an infiltrative retrobulbar mass. What is the most likely site of primary disease?

a. Breast

b. Lung

c. Renal

d. Melanoma

e. Ovarian

Answer 20

33. a. Breast

Most retrobulbar metastases are extraconal (outside the muscle cone).

Neuroblastoma and Ewing’s sarcoma are the most common in children and produce smooth extraconal masses related to the posterior lateral wall of the orbit.

In adults, an infiltrative retrobulbar mass and enophthalmos is characteristic of scirrhous carcinoma of the breast (invasive ductal carcinoma).

Enophthalmia is also considered to be one of the earliest signs of metastatic breast cancer.

Question 21

42. A three week old girl is investigated for a right orbital mass. CT shows a diffuse, poorly marginated mass in the superior temporal quadrant of the orbit. It is separate from the globe and the mass shows diffuse enhancement post-contrast injection. On MRI, the mass is hypointense to fat on T1 but hyperintense on T2. On both sequences, low-signal curvilinear foci are seen within it. What is the most likely diagnosis?

a. Lymphangioma

b. Rhabdomyosarcoma

c. Cavernous haemangioma

d. Retinoblastoma

e. Capillary haemangioma

Answer 21

42. e. Capillary haemangioma

Capillary haemangiomas are the most common vascular orbital masses in children. They typically present at birth or shortly after. CT shows a diffuse, usually poorly marginated mass which shows diffuse contrast enhancement. On MRI the mass is hypointense to fat on T1, and on T2 it is hyperintense to muscle and fat but hypointense compared to fluid. Curvilinear flow voids representing blood vessels are typical within the mass. They tend to grow rapidly over 1st 6 months of life, stop growing during the second year and then slowly involute over years.

Question 22

(Ped) 44. A nine month old presents with leukokoria. Which finding would favour a diagnosis of persistent hyperplastic primary vitreous (PHPV) rather than retinoblastoma (RB)?

a. Calcification

b. Optic nerve enlargement

c. Retinal detachment

d. Microphthalmia

e. Dense vitreous on CT

Answer 22

44. d. Microphthalmia

Primary vitreous normally involutes by the sixth fetal month, but occasionally persists and undergoes hyperplasia. It is the second most common cause of unilateral leukokoria behind retinoblastoma. It may be bilateral as a part of congenital syndromes such as Norrie disease. Key imaging findings are micropthalmia (small hypoplastic globe) with an enhancing central soft-tissue band extending from the lens (retrolental) through the vitreous body to the back of the orbit (i.e. following Cloquet’s canal). Calcifications are not a feature (cf retinoblastoma – the most common cause of orbital calcifications). Both may show a hyperechoic focus on ultrasound and a dense vitreous on CT. PHPV is associated with a small optic nerve whereas retinoblastoma may show optic nerve enlargement due to tumour extension and may also demonstrate macropthalmia.

Question 23

47. A 15 year old girl presents with suspected optic neuritis. Post-contrast T1-weighted imaging shows enhancement and mild enlargement of the right optic nerve. Several months later the girl re-presents with symptoms of myelitis. Sagittal T2-weighted imaging of the spine demonstrates intramedullary T2 hyperintensity and cord expansion extending from C1 to T1. At the time of the initial and subsequent presentations, brain imaging was normal. What is the most likely diagnosis?

a. Multiple sclerosis

b. Sarcoidosis

c. Devic syndrome

d. Neurofibromatosis

e. Ependymoma

Answer 23

47. c. Devic syndrome (DS)

Devic syndrome (neuromyelitis optica (NMO)) is a severe demyelinating syndrome characterized by optic neuritis and acute myelitis. There is substantial evidence that DS is distinct from multiple sclerosis (MS). DS may spare the brain, the spinal lesions are much larger than in MS and the serum autoantibody NMO-IgG is greater than 90% specific for DS patients and is not detected in classical MS patients. The proposed diagnostic criteria for Devic syndrome are optic neuritis and acute myelitis plus at least two of three supporting criteria:
1. Contiguous spinal cord MRI lesion extending over greater than or equal to three vertebral segments.
2. Brain MRI not meeting diagnostic criteria for multiple sclerosis.
3. NMO-IgG seropositive status.

Question 24

QUESTION 1
A 42-year-old woman with known Wegener’s granulomatosis presents with pain on moving her left eye. On examination she has left-sided proptosis and pain on all eye movements. CT of the orbits demonstrates inflammation of the left-sided extraocular muscles and their tendinous insertions with enhancement postcontrast. There is also increased attenuation within the retrobulbar fat as well as enlargement of the lacrimal gland. What is the most likely diagnosis?

A Capillary haemangioma

B Graves’ disease

C Orbital lymphoma

D Orbital pseudotumour

E Retinoblastoma

Answer 24

D Orbital pseudotumour

Involvement of the tendinous insertions, as well as the muscle bellies, is highly suggestive of orbital pseudotumour.

Question 25

QUESTION 11 A 5-year-old boy presents with rapidly progressive right-sided proptosis. On examination, he is noted to have lateral deviation of the right eye but visual acuity is normal. CT of the orbits reveals a large, isodense mass in the superomedial right orbit. The extraocular muscles cannot be seen separately and there is destruction of the medial wall of the bony orbit. The mass displays uniform enhancement postcontrast. What is the most likely diagnosis?

A Capillary haemangioma

B Dermoid cyst

C Intraconal schwannoma

D Retinoblastoma

E Rhabdomyosarcoma

Answer 25

E Rhabdomyosarcoma

This is a highly malignant tumour which is most common in 2-5 year olds.

Question 26

@# QUESTION 12
A 46-year-old woman presents with a painful left eye. She has enophthalmos on clinical examination. CT reveals a mass arising from the greater wing of the left sphenoid with some underlying bone destruction. The mass is poorly marginated and infiltrating die intraconal compartment. What is the most likely diagnosis?

A Caroticocavernous fistula

B Lymphoma

C Metastatic breast carcinoma

D Orbital dermoid

E Orbital varix

Answer 26

C Metastatic breast carcinoma

This is a characteristic appearance of metastatic scirrhous breast carcinoma

Question 27

@# QUESTION 23 A GP requests your advice regarding an 18-month-old girl whose mother has noticed that her left pupil appears white. The GP has performed ophthalmoscopy and is suspicious that there is a retinal mass. Which one of the following is the investigation of choice?

A CT orbits

B MRI orbits

C Orbital radiographs

D Repeat ophthalmoscopy by ophthalmologist

E Ultrasound

Answer 27

A CT orbits

CT is the best initial investigation as it is sensitive to calcification in retinoblastoma. If there is calcification within an ocular mass in a child under 3 years of age, it is considered to be retinoblastoma until proven otherwise.

Question 28

QUESTION 35
A 22-year-old woman presents with visual loss and headaches. On examination, she has bilateral visual field defects and decreased visual acuity. CT reveals foci of calcification at both optic nerve heads. What is the most likely diagnosis?

A Choroidal haemangioma

B Drusen

C Leukaemia

D Optic neuritis

E Sclerosing endophthalmitis

Answer 28

B Drusen

Optic disc drusen are small collections of hyaline material located within the head of the optic nerve (CN II) at variable depths. The earliest signs of drusen formation histologically are small globular or plaque-like deposits in Bruch membrane of hyaline material, present in the majority of individuals, and perhaps congenital in nature.

Question 29

QUESTION 39
A 61-year-old woman presents with a gradual loss of visual acuity in the left eye. She has left-sided proptosis on examination. A CT head postcontrast reveals thickening of the optic nerve/sheath complex with a ‘tram-track’ appearance. There is some associated calcification. What is the most likely

A Cavernous haemangioma

B Lymphoma

C Optic nerve glioma

D Optic nerve haemangioblastoma

E Optic nerve meningioma

Answer 29

E Optic nerve meningioma

Optic nerve meningiomas typically cause tubular thickening of the nerve as opposed to the fusiform thickening seen in gliomas

Question 30

QUESTION 47
A 9-month-old boy is noted to have an absent red reflex in his right eye, following a photograph taken by his family. An ophthalmologist confirms the presence of a retinal mass and a CT is requested. Which one of the following best describes the findings you would expect to see in a case of retinoblastoma on CT?

A Avidly enhancing, non-calcified retinal mass

B Avidly enhancing retinal mass with punctate calcification

C Hyperdense, non-calcified retinal mass

D Poorly enhancing, non-calcified retinal mass

E Poorly enhancing retinal mass with clumped calcification

Answer 30

E Poorly enhancing retinal mass with clumped calcification

Question 31

QUESTION 51
A 63-year-old previously fit and well woman presents to her optician with loss of vision in her left eye. On examination, the visual acuity in the left eye is markedly reduced and the vitreous appears opaque. After ophthalmology review, an MRI is performed and reveals a soft tissue mass on the wall of the globe which is of high signal on Tlw images and low signal on T2w images. What is the most likely diagnosis?

A Cavernous haemangioma

B Ocular metastasis

C Pseudotumour

D Retinoblastoma

E Uveal melanoma

Answer 31

E Uveal melanoma

The signal characteristics are typical of melanoma. Metastases from mucinous adenocarcinomas can have similar signal characteristics

Question 32

QUESTION 60
A 51-year-old man presents with painless swelling of the left eye and is found to have left-sided proptosis on clinical examination. MRI demonstrates low T1 signal and high T2 signal in the left lacrimal gland and superior rectus muscle. These areas display enhancement following contrast administration. The bony orbit appears normal. What is the most likely diagnosis?

A Capillary haemangioma

B Cavernous haemangioma

C Graves’ disease

D Lymphoma

E Metastasis

Answer 32

D Lymphoma

Orbital lymphoma typically presents with painless orbital swelling. It moulds to the bony orbital contours rather titan causing bony destruction (although this can occur in very aggressive cases).

Question 33

QUESTION 66
A 38-year-old woman presents with unilateral right-sided proptosis. CT of the orbits shows an increase in the volume of retro-orbital fat with subtle hyperdensity. Which one of the following additional features suggests a diagnosis of orbital pseudotumour rather than Graves’ disease?

A Destruction of the medial wall of the bony orbit

B Enlargement and enhancement of the inferior rectus muscle

C Enlargement and enhancement of the inferior rectus muscle and its tendinous insertion

D Involvement of the inferior and medial rectus muscles bilaterally

E Unilateral exophthalmos

Answer 33

C Enlargement and enhancement of the inferior rectus muscle and its tendinous insertion

Involvement of a single unilateral extraocular muscle and its tendinous insertion is highly suggestive of orbital pseudotumour rather than thyroid ophthalmopathy. The condition does not cause bony destruction

Question 34

QUESTION 73
A 23-year-old man presents with right-sided proptosis. His visual acuity is normal. CT reveals a well-defined, hyperdense mass posterior to the globe which spares the orbital apex. The medial and lateral orbital walls are moulded around the mass but there is no evidence of bony destruction. What is the most likely diagnosis?

A Capillary haemangioma

B Cavernous haemangioma

C Ocular metastasis

D Optic nerve glioma

E Orbital pseudotumour

Answer 34

B Cavernous haemangioma

These are the most common intraorbital tumours in adults.

Question 35

QUESTION 78
A patient has an orbital CT which shows a hyperdense intra- and extraconal mass containing multiple calcified phleboliths. The mass displays heterogeneous enhancement. What is the likely diagnosis?

A Optic nerve meningioma

B Orbital varix

C Pseudotumour

D Retinoblastoma

E Rhabdomyosarcoma

Answer 35

B Orbital varix

A varix is a dilated vein or group of veins. The usual presentation is that of intermittent proptosis which is caused by the Valsalva manoeuvre or postural change (due to an increase in intracranial pressure). Calcified phleboliths are pathognomonic if present.

Question 36

(Ped) QUESTION 78
A 5-year-old child with neurofibromatosis type 1 (NF1) presents with a unilateral painless proptosis and reduced visual acuity. He undergoes both CT and MRI examinations of the orbits and brain. When assessing for an optic nerve glioma, which one of the following statements is true?

A Calcification of the optic tract on CT would suggest an optic nerve glioma.

B Extension of the tumour into the subarachnoid space is recognised.

C On Tlw images, optic nerve gliomas yield high signal.

D Optic nerve gliomas are usually nonenhancing.

E The commonest location of an optic pathway glioma is within the optic chiasm.

Answer 36

B Extension of the tumour into the subarachnoid space is recognised.

Optic pathway gliomas are the most commonly seen intracranial abnormality in NF1. The commonest location in children is within the optic nerve rather than the chiasm.

Question 37

18. Which one of the following orbital pathologies typically arises from the intraconal compartment?

A. Cavernous haemangioma.

B. Adenocystic carcinoma.

C. Rhabdomyosarcoma.

D. Dermoid.

E. Orbital pseudotumour.

Answer 37

18. A. Cavernous haemangioma.

The orbital compartments are split up into extraconal, conal, intraconal, and globe. The extraconal compartment consists of fat, lacrimal gland, and bony orbit. Pathology in this region includes infection, neurofibroma, adenocarcinoma, mucoepidermoid and adenoid cystic carcinoma, neoplasia of bone, and lymphoma. Conal pathology (muscle) includes rhabdomyosarcoma, thyroid eye disease, and idiopathic orbital inflammation (pseudotumour). The intraconal compartment consists of fat, lymph nodes, vessels, nerves, and the optic nerve sheath complex. Pathology in this region includes venolymphatic malformation, haemangioma, arteriovenous malformation, optic nerve meningioma/glioma, and lymphoma. Pathology in the globe includes retinoblastoma, metastasis, and melanoma.

Question 38

20. A 54-year-old lady with a history of exophthalmos undergoes a CT scan of orbits for assessment. There is spindle-shaped enlargement of extra-orbital musculature that does not involve the tendinous insertions. Which pair of muscles is most likely to be involved?

A. Superior and inferior.

B. Superior and medial.

C. Superior and lateral.

D. Inferior and medial.

E. Inferior and lateral.

F. Medial and lateral.

Answer 38

20. D. Inferior and medial.

The question refers to Graves ophthalmopathy, where enlargement of the extraocular muscles is observed, with sparing of the tendinous insertions. This is in distinction to idiopathic orbital inflammatory syndrome, where the muscle swelling typically involves the tendinous insertions. In Graves ophthalmopathy, the extra-orbital muscles are involved with decreasing frequency as follows: inferior, medial, superior, and lateral recti.

Question 39

21. A 7-year-old boy presents with rapid onset right proptosis. CT shows an extraconal mass in the right orbit with irregular margins. There is evidence of intraconal and intracranial extension. On MRI, the lesion is of decreased signal on T1WI, increased signal on T2WI, and shows relatively uniform enhancement. What is the most likely diagnosis?

A. Retinoblastoma.

B. Non-Hodgkin lymphoma.

C. Capillary haemangioma.

D. Ruptured dermoid cyst.

E. Rhabdomyosarcoma.

Answer 39

21. E. Rhabdomyosarcoma.

The clinical and radiological features described are typical of rhabdomyosarcoma. It usually presents in the first decade of life with a rapidly growing mass causing proptosis. The globe is often distorted and displaced, but rarely invaded. The lesion is aggressive and there may be extension into the sinuses or intracranial compartment, and bony destruction can occur. NHL is usually found in older adults, but it can occur in older children or adolescents. Unlike rhabdomyosarcoma, NHL commonly causes lacrimal gland involvement, may be hypointense on T2WI, and encases rather than distorts the globe. Capillary haemangioma typically presents in the first few months of life. They have a proliferative phase for approximately 12 months following diagnosis and then are stable, before gradually involuting over a period of years. These lesions show rapid and persistent enhancement on CT and MRI. On unenhanced MRI, it is typically iso- to hyperintense relative to muscle on T1WI and moderately hyperintense on T2WI, with flow voids at the periphery of or within the tumour. A ruptured dermoid cyst can mimic a rhabdomyosarcoma both clinically and radiologically, but one might expect to see calcification or fatty or cystic components in the native lesion. Retinoblastoma is an intraorbital lesion.

Question 40

22. A 10-year-old girl presents with gradual onset proptosis in the left eye and is noted to have restricted left eye movements. An MRI scan is performed and this demonstrates a poorly circumscribed lobulated lesion that involves both the intraconal and extraconal compartments. The lesion has mixed signal intensity on T1WI, with areas of increased and decreased signal. It is mostly of increased signal on T2WI and there are areas containing a fluid– fluid level. Post contrast, there is heterogenous enhancement. What is the most likely diagnosis?

A. Venous-lymphatic malformation.

B. Orbital varix.

C. Cavernous haemangioma.

D. Capillary haemangioma.

E. Haemangiopericytoma.

Answer 40

22. A. Venous-lymphatic malformation.

Venous-lymphatic malformation (previously known as a lymphangioma) typically has a presentation in childhood. MRI is the modality of choice for diagnosis, as fluid–fluid levels are almost pathognomic of this condition and these represent areas of haemorrhage of varying ages. The MRI findings are as those described and there are typically no large feeding vessels or flow voids. The lesion is predominantly extraconal, but can insinuate into the intraconal compartment. Capillary haemangioma also presents in childhood, but may be apparent clinically and on MRI there are not typically fluid–fluid levels, but there may be flow voids within the lesion from prominent vessels. Also, enhancement is usually more rapid and persistent in capillary haemangioma than in venous-lymphatic malformation. Orbital varices usually present in young adults and on imaging have the appearance of dilated, tortuous vessels. Cavernous haemangioma typically presents in adulthood. They are usually well-circumscribed and most often occur in the lateral aspect of the retrobulbar intraconal space. On CT, they are slightly hyperattenuating prior to contrast and may contain phleboliths. On MRI, they are isointense to muscle on T1WI and hyperintense on T2WI. They show progressive enhancement on multiphase dynamic imaging. Haemangiopericytomas are rare vascular tumours that are more often seen in adults than children. Large lesions may show bony erosion and they do not typically have fluid–fluid levels on CT or MRI.

Question 41

23. A 20-year-old female with a history of neurofibromatosis presents with reduced visual acuity in the right eye. She subsequently has CT and MR imaging of the orbits to assess for a tumour relating to the right optic nerve. Which of the following findings on imaging would be more suggestive of the presence of an optic nerve glioma, rather than a meningioma arising from the optic nerve sheath?

A. Presence of the ‘tram-track’ sign.

B. Presence of optic canal widening.

C. Presence of marked intense tumour enhancement.

D. Presence of calcification.

E. Presence of bony hyperostosis.

Answer 41

23. B. Presence of optic canal widening.

The presence of a widened optic nerve canal occurs in up to 90% of cases of optic nerve glioma. While it can also occur in meningioma, it is more common in glioma and some cases of meningioma may even have a narrowed canal secondary to bony hyperostosis. The ‘tram-track’ sign is typically associated with meningioma and refers to the more avidly enhancing meningioma surrounding the non-enhancing optic nerve on axial CT and MR imaging of the orbit. Although both meningioma and glioma enhance following intravenous contrast, it is meningioma that is more typically associated with marked intense enhancement. Calcification and bony hyperostosis are features associated with meningioma. Calcification is rare in gliomas, unless they have previously undergone radiotherapy.

Question 42

(Ped) 56. An 18-month-old boy is referred for CT after presenting with a right-sided white eye reflex (leucocoria). Which radiological feature is most in keeping with a diagnosis of retinoblastoma, as opposed to non-neoplastic causes of leucocoria (pseudoretinoblastoma)?

A. Contrast enhancement.

B. Calcification.

C. Microophthalmia.

D. Mass extension into the vitreous.

E. Secondary retinal detachment.

Answer 42

56. B. Calcification.

This is the most specific feature of retinoblastoma and is apparent in 95% of cases. Other features of retinoblastoma include hyperattenuating mass extending into the vitreous and secondary retinal detachment. Contrast enhancement is seen in <30% of cases. The globe is normal sized. The non-neoplastic causes of leucocoria, the so-called pseudoretinoblastomas, include persistent hyperplastic primary vitreous (PHPV), Coat’s disease, and toxocara endophthalmitis. CT findings in PHPV include micro-opthalmia and an enhancing retrolental mass. Coat’s disease is a vascular malformation of the retina and presents with a hyperattenuating globe and an enhancing subretinal exudate on CT. CT features of toxocara are non-specific and similar to Coat’s disease. Secondary retinal detachment may be seen. None of the pseudoretinoblastomas exhibit calcification.

Question 43

2 A five-month-old baby girl was being investigated for blindness. On CT both her globes were elongated with a cone-shaped deformity affecting the posterior globe, which involved the optic nerve. The defect passed inferiorly and communicated with vitreous. The girl had cardiac abnormalities and choanal atresia. What is the eye abnormality?

a Coloboma

b Congenital glaucoma

C Rubella retinitis

d Trauma

e Orbital haematoma

Answer 43

2 Answer A: Coloboma

A Coloboma is a congenital defect in the orbit, which is caused by incomplete closure of the choroidal fissure. They are typically cone or notched shaped and commonly affect the inferomedial portion of the globe. They are bilateral in 50% and can occur in association with other congenital abnormalities such as encephalocele, agenesis of the corpus callosum or as part of a syndrome (CHARGE syndrome).

Question 44

3 A six-month-old child has bilateral leukocoria. On CT there were bilateral solid smooth lobulated hyperdense lesions with nodular calcification within both orbits. The tumours were in the posterolateral region and were indistinguishable from the wall of the globe. The globes were both of normal size. What other abnormality to be looked for on CT?

a Cortical tubers

b Subependymal heterotopia

c Pineoblastoma

d Persistent hyperplastic primary vitreous

e Coat’s disease

Answer 44

3 Answer C: Pineoblastoma

Leukokoria is a white papillary light reflex. This can be caused by tumours (retinoblastomas, retinal hamartomas), developmental (PHPV, Coat’s disease), infections and trauma. These bilateral orbital masses are retinoblastomas and this is a very typical description. The peak age is 18 months and males and females are affected equally. Two-thirds are sporadic and of these only 30% are bilateral while in the hereditary form 70% are bilateral. When bilateral retinoblastomas are associated with pineoblastomas they are called trilateral retinoblastomas.

Question 45

4 A CT head on a 60-year-old male demonstrated bilateral small calcific densities overlying the junction of the retina and optic nerve. The intraconal portion of the optic nerve appeared normal. No other abnormalities were seen on CT. What is the most likely diagnosis?

a Retinoblastoma

b Drusen

c Coat’s disease

d Bilateral optic gliomas

e Choroidal osteoma

Answer 45

4 Answer B: Drusen

Drusen are the accumulation of calcified hyaline material typically in the region of the optic nerve. It is bilateral 75% of the time and is often familial. Typically, on CT they are flat discs of calcification overlying the optic nerves. Patients present with headaches and visual field defects.

Question 46

5 A newborn child is noted to have leukocoria. A CT was performed. What feature makes persistent hyperplastic primary vitreous more likely than retinoblastoma?

a A calcified intra-orbital mass

b Microphthalmia

c A diffuse infiltrating mass

d Moderately high signal on Ti

e Bony destruction

Answer 46

5 Answer B: Microphthalmia

Persistent hyperplastic primary vitreous (PHPV) is a rare condition caused by persistence of the primary vitreous, which presents in newborns with leukocoria. The orbit is small and deformed with a flattened lens and the optic nerve is small. PHPV is hypervascular and prone to bleeding hence the vitreous is dense due to repeated haemorrhage. No calcification is demonstrated. Retinoblastomas cause expansion of the globe, are calcified and cause bony destruction. Both tumours can be high signal on T1-weighted imaging.

Question 47

6 A 45-year-old male complained of worsening vision. On cross-sectional imaging the left optic nerve appeared thickened. What feature makes optic glioma more likely than optic nerve sheath meningioma?

a A unilateral mass

b Hyperostosis affecting the optic canal

c Diffuse homogeneous enhancement

d Calcification

e Kinking and buckling of the optic nerve

Answer 47

6 Answer E: Kinking and bucking of the optic nerve

Question 48

@#e 7 A 55-year-old gentleman was investigated for sudden onset visual loss affecting the right temporal region. Ultrasound of the globe demonstrated right-sided retinal detachment with an associated well-defined flat echogenic mass was seen. An uveal melanoma was suspected and a MRI scan performed. What are the likely signal characteristics of the lesion?

a High signal on both Ti- and T2-weighted imaging

b High signal on T1-weighted imaging and intermediate on T2

C High signal on T1-weighted imaging and intermediate on T2

d High signal on T1-weighted imaging and intermediate on T2

e Low signal on both Ti- and T2-weighted imaging

Answer 48

7 Answer A: High signal on both Ti- and T2-weighted imaging

Orbital melanomas are high signal on both Ti- and T2-weighted imaging. They are the commonest intraocular primary in adults, arise from the choroids plexus and are associated with retinal detachment, vitreous haemorrhage and glaucoma.

Question 49

43 A 22-year-old female rear-seat passenger suffered a high-speed road traffic accident and presented to the Emergency Department with several left temporal facial injuries. Following stabilisation of her bony injuries she was discharged. A week later she developed painful left orbital swelling and third nerve palsy. A post-contrast CT was unremarkable barring some fullness of the left orbital apex and mild enlargement of the left superior ophthalmic vein. A catheter angiogram revealed early opacification of the left superior ophthalmic vein and a vascular blush posteriorly. What is the most likely diagnosis?

a Dural fistula

b Traumatic ICA aneurysm

C Caroticocavernous fistula

d Carotid dissection

e Cavernous angioma

Answer 49

43 Answer C: Caroticocavernous fistula (CCF)

A CCF is a dural AV fistula characterised by abnormal arteriovenous shunting within the cavernous sinus. It can result from blunt/penetrating trauma, although the majority are thought to be spontaneous. Classical presentation is with pulsatile proptosis; chemosis, diplopia and cranial nerve palsies can also occur. CT and MRI show a markedly enlarged superior ophthalmic vein and prominent cavernous sinus. Congestion of the extraocular muscles maybe seen. Angiography is required for confirmation and treatment. Balloon occlusion of the fistula is the treatment of choice.

Question 50

(Ped) 2 An 18-month-old child is being investigated for reduced visual acuity and strabismus. She undergoes an ultrasound of the orbit, which demonstrates a heterogeneous, hyperechoic cystic intraocular mass with retinal detachment. What is the most likely diagnosis?

a Retinoblastoma

b Persistent hyperplastic primary vitreous

C Retinal astrocytoma

d Rhabdomyosarcoma

e Varix of the orbit

Answer 50

2 Answer A: Retinoblastoma

Retinoblastoma is a rare congenital malignant tumour of the retina. There is a non-inherited (66% of cases) and an inherited form. They usually present between one year and 18 months old with leukocoria or squint. The cysts are due to tumour necrosis. Retinal detachment is present in all cases; acoustic shadowing is only present in 75%. Vitreous haemorrhage is frequent. Persistent hyperplastic primary vitreous is a band from the retina to the posterior surface of the lens or central anechoic line. Retinal astrocytoma is commonly confused with retinoblastoma but is much less common. Rhabdomyosarcoma is the commonest tumour of the orbit in childhood but originates from the orbit, not the retina, and usually presents with exophthalmos at a much later age.

Question 51

3 A 55-year-old female was admitted with a worsening headache. On imaging the right optic nerve appeared thickened with linear plaque-like calcification & optic canal hyperostosis. What pattern of enhancement is most likely?

a Patchy enhancement of the optic canal

b No enhancement

c Generalised tram track enhancement

d Peripheral enhancement

e Avid enhancement with flow voids

Answer 51

3 Answer C: Generalised tram track enhancement

This patient has an optic nerve sheath meningioma. These typically demonstrate uniform bright enhancement with a non-enhancing optic nerve. Patchy enhancement of the optic nerve is seen in optic nerve gliomas.

Question 52

5 A 45-year-old woman with known multiple sclerosis complained to her GP that she had visual loss. On examination she was found to have upper rightsided quadrantanopia. Where is she likely to have a new plaque?

a Right optic nerve

b Optic chiasm

c Left lateral geniculate nucleus

d Right optic tracts

e Left optic radiation

Answer 52

5 Answer E: Left optic radiation

Monocular visual loss is due to a defect in the optic nerve. Bitemporal hemianopia is due to a defect at the optic chiasm level. Right-sided homonymous hemianopia is caused by a defect in the contralateral optic tract or through any part of the contralateral optic radiation. Right upper outer quadrantanopia is due to a defect in part of the optic radiation. Central bilateral homonymous hemianopia is due to a defect in the contralateral primary visual cortex.

Question 53

6 A five-year-old boy was noted by his parent to be bumping into things on his left. On examination he was found to have a soft-tissue mass affecting his left retina. On CT there was a poorly enhancing mass causing irregularity of the orbit and surrounding conal fat haziness. This mass was most likely to be a secondary from which tumour?

a Neuroblastoma

b Wilms’

C Sarcoma

d Leukaemia

e Medulloblastoma

Answer 53

6 Answer A: Neuroblastoma

The most common orbital metastases in children are from neuroblastomas followed by Ewing’s tumours and leukaemia. In adults breast and lung are the most common primaries causing intraorbital lesions. The deposits are typically intraocular.

Question 54

(Ped) 19 A four-year-old boy presented with loss of visual acuity and a change in iris pigmentation. A CT of his brain and orbits showed a diffuse thickening of the left optic nerve. An MRI was then performed, which showed the abnormality to be isodense to the cortex and hypodense to the white matter on T1-weighted images, and hyperdense to the cortex and white matter on T2-weighted images. It was hypodense to orbital fat on all sequences. There was intense enhancement postgadolinium. Which of the following is the most likely diagnosis?

a Isolated meningioma

b Neurofibromatosis type 1

c Oligodendroglioma

d Subdural haematoma

e Previous cranial trauma

Answer 54

19 Answer B. Neurofibromatosis type 1

The imaging findings are those of an optic nerve glioma. The change in iris pigmentation described is likely to be due to Lisch nodules (pigmented iris hamartomas).

Question 55

3 A 65-year-old known arteriopath was admitted via the emergency eye clinic with new onset rightsided homonymous hemianopia (hemianopsia). What part of the optic pathway is most likely to be
affected?

a Left optic tract

b Right primary visual cortex

C Right optic radiation

d Optic chiasm

e Left optic nerve

Answer 55

3 Answer A: Left optic tract

Monocular visual loss is due to a defect in the optic nerve. Bitemporal hemianopia is due to a defect at the optic chiasm level. A homonymous hemianopia is caused by a defect in the contralateral optic tract or through all the contralateral optic radiation. Right upper outer quadrantanopia is due to a defect in part of the optic radiation. Central bilateral homonymous hemianopia is due to a defect in the contralateral primary visual cortex.

Question 56

4 A 42-year-old female is seen in the emergency eye clinic with a left-sided proptosis and chemosis. What features on imaging make thyroid eye disease more likely than pseudotumour?

a Intraconal fat haziness

b Enhancement of the fat

c Thickening and enhancement of Tenon’s capsule (fascia bulbi)

d Lacrimal gland enlargement

e Swelling limited to the muscle bellies of the recti muscles

Answer 56

4 Answer E: Swelling of the rectus muscles and levator palpebrae only

Thyroid eye disease is limited to the muscle bellies of rectus and levator palpebrae muscles and Tenon’s capsule tends to be spared. This is not the case in pseudotumour. Fat haziness is seen in both thyroid eye disease and pseudotumour. In pseudotumour there is enhancement of the fat with contrast, and lacrimal gland enlargement occurs in 5% of cases.

Question 57

5 A 44-year-old hyperthyroid woman develops chemosis, proptosis and lid lag affecting the right eye. She underwent a CT. Which orbital muscle is the most commonly affected?

a Lateral rectus

b Superior rectus

C Medial rectus

d Inferior oblique

e Inferior rectus

Answer 57

5 Answer E: Inferior rectus

This patient has Graves’ eye disease, which is an autoimmune disorder caused by long-acting thyroid simulating factor. It is commonly bilateral (75 %) and results in hypertrophy of the muscle belly with sparing of the tendon insertions. The most commonly affected muscle is the inferior rectus followed by the medial, superior and then the lateral recti.

Question 58

6 A 34-year-old male with known Burkitt’s lymphoma has a new right-sided proptosis. Where is the most likely site of the lymphomatous deposit?

a Rectus muscles

b Bony destruction of the sphenoid wing

C Intraconal

d Intraorbital

e Lacrimal gland

Answer 58

6 Answer E: Lacrimal gland

Orbital lymphoma is typically non-Hodgkin’s B-cell lymphoma and occurs in middle age. It is usually associated with lymphomatous deposits elsewhere in the body. The most common site is extraconal, within the lacrimal glands. On imaging lymphoma within the lacrimal gland is usually seen as welldefined high-density mass.

Question 59

7 A 76-year-old man with deranged liver enzymes underwent an MRI for investigation of a possible cerebrovascular event. On T1-weighted MR he was noted to have an incidental 0.5-cm high-signal lesion in his right choroid. Apart from age-related small-vessel changes within the periventricular white matter the rest of the MRI was within normal limits. What is the most likely diagnosis?

a Haemorrhagic cysts

b Choroidal lipomas

C Kayser-Fleischer rings

d Melanoma

e Foreign body

Answer 59

7 Answer D: Melanoma

This patient has metastatic uveal melanoma. Medical students are always taught beware of the man with the glass eye and the large liver! Uveal melanoma is the most common primary intraocular neoplasm in adults. It occurs in patients aged 50-70 and is usually choroidal and unilateral. On MRI the lesion is of high signal on T1-weighted images and it is hyperdense on CT. These lesions metastasise to the lung, liver and optic nerve and prognosis is poor.

Question 60

68 A 55-year-old woman complained of left retro-orbital pain and double vision. On examination she was found to have left III, IV and VI nerve palsies. She has no past medical history and is otherwise well. Imaging demonstrated abnormalities in the ipsilateral cavernous sinus and superior orbital fissure. What is the most likely diagnosis?

a Moyamoya

b Ramsay Hunt syndrome

C Herpes simples encephalitis

d Tolosa-Hunt syndrome

e Sarcoidosis

Answer 60

68 Answer D: Tolosa-Hunt syndrome

Tolosa-Hunt syndrome is an idiopathic inflammatory disease with some similarity to orbital pseudotumour. Patients present with recurrent bouts of retro-orbital pain associated with cranial nerve palsies affecting the III, VI, VI and VI nerves. Symptoms last for days to weeks and respond rapidly to steroid therapy. The above features are typical. Ramsay Hunt syndrome is due to herpes zoster infection involving the geniculate ganglion giving acute facial nerve paralysis, pain in the ear and a typical rash.

Question 61

19. A 25-year-old man presents with painless progressive proptosis. CT shows a soft tissue lesion with microcalcifications in the left orbit. On MRI, T1 axial and coronal images show a soft tissue mass isointense to adjacent muscles in the extraconal plane while the T2 images show the hyperintense septated lesion. The lesion avidly enhances with gadolinium. What is the most likely diagnosis?

(a) Cavernous haemangioma

(b) Orbital pseudotumour

(c) Neurofibroma

(d) Dermoid cyst

(e) Haemangiopericytoma

Answer 61

19. (a) Cavernous haemangioma

This is the most common orbital mass in adults and is the most common vascular malformation of the orbit. CT demonstrates the location of the lesion and microcalcifications. Remodelling of the bone may be seen. MRI features are typical as given.

Question 62

35. A 25-year-old man presents with unilateral proptosis, chemosis, reduced visual acuity and a bruit over his right orbit. Gadolinium-enhanced MRI of the orbits shows abnormal contrast enhancement of the right periorbital soft tissues and extraocular muscles. The superior ophthalmic vein is also dilated. What is the most likely diagnosis?

(a) Carotid-cavernous fistula

(b) Graves’ disease

(c) Orbital pseudotumour

(d) Optic nerve glioma

(e) Cavernous haemangioma orbit

Answer 62

35. (a) Carotid-cavernous fistula

Important imaging findings include: extraocular muscle enlargement, proptosis, chemosis and dilatation of ipsilateral cavernous sinus and superior ophthalmic vein. Graves’ disease affects older ages and bilateral involvement is typical. An orbital pseudotumour is a non-specific inflammation involving any area of orbit. Orbitalbruit and a dilated superior ophthalmic vein are not usually seen.

Question 63

(Ped) 47. A 12-year-old by presents with progressive proptosis and a swollen right eye. MRI shows a diffusely infiltrating extraocular mass in the right orbit which returns intermediate signal on T1 and high signal on T2 with flow voids. What is the most likely diagnosis?

(a) Haemangioma

(b) Rhabdomyosarcoma

(c) Metastasis

(d) Lymphoma

(e) Graves ophthalmoplegia

Answer 63

47. (a) Haemangioma

These are benign tumours which can grow to cause progressive proptosis. Haemorrhage may present with acute symptoms and swelling. Flow voids, when present, are highly suggestive of a haemangioma.

Question 64

48. A 42-year-old woman presents with bilateral proptosis. CT of the orbits shows increased bulk of the rectus muscles and a dilated superior ophthalmic vein. What is the most likely diagnosis?

(a) Graves’ disease

(b) Orbital cellulitis with myositis

(c) Orbital pseudotumour

(d) Sarcoidosis

(e) Non-Hodgkin’s lymphoma

Answer 64

48. (a) Graves’ disease

Graves’ ophthalmopathy (thyroid eye disease) features bilateral exophthalmos with bilateral enlargement of the extraocular muscles. The condition particularly affects the inferior, medial and superior rectus muscles.

Question 65

(Ped) 48. A 6-year-old boy presents with protuberant right eye and pain. Blood tests are normal. CT shows a 3 cm irregular, extraconal mass having focal area of low attenuation and patchy contrast enhancement. On MRI, the lesion is isointense to muscle on T1 and high signal on T2. What is the most likely diagnosis?

(a) Orbital abscess

(b) Haemangioma

(c) Dermoid

(d) Rhabdomyosarcoma

(e) Epidermoid

Answer 65

48. (d) Rhabdomyosarcoma

This is the most common primary orbital tumour in childhood. This usually arises from the mesenchymal tissues and the lesion is usually non-invasive

Question 66

(Ped) 16. Which of the following are correct regarding retinoblastoma (T/F)

(a) Is the most common intra-ocular malignancy in childhood.

(b) Ultrasound demonstrates a hypoechoic mass in the posterior globe.

(c) Is associated with pineblastoma.

(d) Is bilateral in 66 %.

(e) CT shows calcification in 90 %.

Answer 66

Answers:

(a) Correct
(b) Not correct
(c) Correct
(d) Correct
(e) Correct

Explanation:

Retinoblastoma is the most common intraocular neoplasm of childhood. It appears as hyperechoic mass on ultrasound with variable shadowing due to calcification and heterogeneity due to necrosis and/or hemorrhage.

Question 67

14. Concerning orbital mass lesions: (T/F)

(a) 50% of patients with optic nerve glioma have neurofibromatosis Type 1.

(b) On MRI, retinoblastoma usually enhances following intravenous gadolinium.

(c) Rhabdomyosarcoma of the orbit presents with rapid onset proptosis and visual loss.

(d) Inflammatory orbital pseudotumour involves the muscle tendons.

(e) 60-80% of children with retinoblastoma have bilateral tumours.

Answer 67

Answers:

(a) Not correct
(b) Correct
(c) Not correct
(d) Correct
(e) Not correct

Explanation:

25% of the patients with optic nerve glioma have neurofibromatosis type I however only 15% of the patients with neurofibromatosis type I have optic nerve glioma. In the rhabdomyosarcoma of the orbit, there is rapid onset of proptosis however vision is spared. Only 20-40% of retinoblastomas occur bilaterally in children.

Question 68

21. Concerning the differentiation between optic nerve glioma and optic nerve sheath meningioma: (T/F)

(a) A widened optic canal is seen more commonly in optic nerve glioma.

(b) Optic nerve sheath meningioma affects an older age group.

(c) Optic nerve glioma typically shows the ‘tram-track’ sign on enhancement.

(d) Calcification is more commonly seen with optic nerve glioma.

(e) Optic nerve glioma may cause orbital hyperostosis.

Answer 68

Answers:

(a) Correct
(b) Correct
(c) Not correct
(d) Not correct
(e) Not correct

Explanation:

Optic nerve sheath meningioma affects older age usually middle aged woman. Calcification can be seen with optic nerve meningioma but is the rarely seen with optic nerve glioma. Optic nerve sheath meningioma typically shows the tram track sign on enhancement Optic nerve sheath meningioma causes orbital hyperostosis.

Question 69

24. Concerning intraorbital pathology: (T/F)

(a) The lacrimal gland is the most frequently involved orbital structure in idiopathic inflammatory pseudotumour.

(b) Idiopathic inflammatory pseudotumour is unilateral in 40-50% of cases in adults.

(c) Optic nerve glioma is the commonest tumour arising from the optic nerve sheath complex.

(d) Use of steroids differentiates idiopathic inflammatory pseudotumour from lymphoma.

(e) Thyroid eye disease is the most common disorder affecting the orbit.

Answer 69

Answers:

(a) Correct
(b) Not correct
(c) Correct
(d) Not correct
(e) Correct

Explanation:

Pseudotumour is unilateral in 80% of the cases in adults. Use steroids in differentiating pseudotumour from lymphoma is not useful.