6. Head and Neck p345-349 (Orbits)

Question 1

Coloboma (3)

Answer 1

Focal discontinuity of the globe (failure of choroid fissure to close).
Usually posterior.
Unilateral is likely sporadic. Bilateral = CHARGE syndrome (Coloboma, Heart, GU, ears)

Question 2

Persistent Hyperplastic Primary Virteous (PHPV). (4)

Answer 2

Failure of embryonic occular blood supply to regress.
Can lead to retinal detachment.
Classic look is small eye (microphthalmia) with increased density in the vitreous.
No calcifications.

Question 3

Coat’s disease (5)

Answer 3

Due to retinal telangiectasias, results in leaky blood and subretinal exudate.
Can lead to retinal detachment.
Seen in young boys, usually unilateral.
NOT calcified (unlike retinoblastoma).
Smaller globe (unlike retinoblastoma).

Question 4

Retinal detachment (3)

Answer 4

Can occur due to PHPV or Coats.
Can also be due to trauma, sickle cell or old age.
Imaging: V or Y shaped appearance due to lifted up retinal leaves and subretinal fluid (as seen in PHPV).

Question 5

Globe size trivia (4)

Answer 5

Retinoblastoma and toxocariasis - normal size.
PHPV - small size, normal birth age
Retinopathy of prematurity - bilateral small
Coats - smaller size

Question 6

Orbital nerve glioma (5)

Answer 6

Almost always <20YO.
Expansion and enlargement of the entire nerve.
Bilateral associated with NF1.
Most often WHO grade 1 pilocystic astrocytomas.
If sporadic, can be GBMs, highly aggressively.

Question 7

Optic nerve sheath meningioma (2)

Answer 7

“tram track” calcifications or “doughnut” appearance with circumferential enhancement around the optic nerve.

Question 8

Orbital pseudotumour (5)

Answer 8

IgG4 idiopathic inflammatory conditions, involving the extraoccular muscles.
Looks like expanded muscle.
Painful, unilateral, most commonly involves lateral rectus and doesn’t spare the myotendinous insertions.
Graves does not cause pain and does spare the myotendinous insertions, unlike this.
Gets better with steroids. Classically T2 dark.

Question 9

Tolosa Hunt syndrome (4)

Answer 9

Histology same as orbital pseudotumour, but instead involves cavernous sinus.
Painful (just like pseudotumour), presents with multiple cranial nerve palsies.
Responds to steroids like a pseudotumour.

Question 10

Lymphocytic hypophysitis (3)

Answer 10

Same as orbital pseudotumour and tolosa hunt, except it’s pituitary gland.
Enlarged pituitary stalk, in a post partum/3rd trimester woman.
Looks like pituitary adenoma, but classically T2 dark rim

Question 11

Dermoid (3)

Answer 11

Most common benign congenital orbital mass.
Usually superior and lateral, arising from the frontozygomatic suture, and presenting in the first 10 years of life.
Contains fat, like any dermoid.

Question 12

Rhabdomyosarcoma (3)

Answer 12

Most common extra-occular orbital malignancy in children (dermoid is most common benign orbital mass in child).
40% are in head and neck, and then most common in the head and neck.
Still rare overall

Question 13

Metastatic neuroblastoma (3)

Answer 13

Classic appearance of “Raccoon eyes” on physical exam.
Classic location is periorbital tumour infiltration with associated proptosis.
Basilar skill fracture can also cause the raccoon eyes.

Question 14

Metastatic breast cancer (2)

Answer 14

Unlike primary orbital tumours which cause proptosis, breast cancer mets cause desmoplastic reaction and enophthalmos

Question 15

Lymphoma (4)

Answer 15

Association with Chlamydia Psittaci (associated with birds) and MALT lymphoma of the orbit.
Usually involves upper outer orbit, closely associated with lacrimal gland.
Enhances homogenously, restricts diffusion, just like the brain.

Question 16

Melanoma (2)

Answer 16

Most common intra-occular lesion in adult. Usually the answer of enhancing soft tissue mass in the back of an adult’s eye.
“Collar button shaped” - related to Bruch’s membrane

Question 17

Retinoblastoma (5)

Answer 17

Most common primary globe malignancy.
Due to faulty RB suppressor gene on chromosome 13, also responsible for osteosarcomas, hence risk of facial osteosarcoma with radiotherapy.
Calcification in globe of a child is usually this.
Globe should be normal in size or bigger.
Usually seen before age 3.
Can be bilateral in 30%, trilateral (both eyes and pineal gland) or quadrilateral (both eyes, pineal and suprasellar)

Question 18

Lymphangioma (5)

Answer 18

Mix of venous and lymphatic malformations.
Ill-defined and lack a capsule.
Usually infiltrative (multispacial), involving pre septal, septal, post septal and extraconal locations.
Fluid-fluid levels are most likely finding in questions.
Do NOT increase with valsalva.

Question 19

Varix (4)

Answer 19

Occur due to weakness in post capillary venous wall, giving massive dilatation of the valveless orbital veins.
They distend with valsalva.
Most common cause of spontaneous orbital haemorrhage.
Can thrombose and present with pain.

Question 20

Carotid-cavernous fistula (3)

Answer 20

Direct (due to trauma) or indirect (occurs randomly, usually postmenopausal women).
Direct is a communication between intracavernous ICA and cavernous sinus.
Indirect is dural shunt between meningeal branches of the ECA and cavernous sinus.

Question 21

Pulsatile exophthalmus causes (2)

Answer 21

C-C fistula is commonest.
NF1 can also cause it from sphenoid wing dysplasia

Question 22

Pre-septal/post-septal cellulitis (4)

Answer 22

Location of orbital infections are described by their relationship to the orbital septum.
Orbital septum originates from the periosteum of the orbit, and inserts in the palpebral tissue along the tarsal plate.
Pre-septal infections usually start in adjacent structures, usually teeth and face
Post-septal infections are usually from paranasal sinusitis.

Question 23

Dacrocystitis (3)

Answer 23

Inflammation and dilatation of the lacrimal sac.
Well circumscribed round rim enhancing lesion, centered in the lacrimal fossa.
Due to obstruction then bacterial infection (staph and strep)

Question 24

Orbital subperiosteal abscess (2)

Answer 24

Inflammation under the periosteum can progress to abscess formation.
Usually associated with ethmoid sinusitis.

Question 25

Optic neuritis (4)

Answer 25

Enhancement of optic nerve without enlargement of the nerve/sheath complex.
70% unilateral, and painful.
Often see intracranial or spinal cord demyelination, in the setting of Devics (neuromyelitis optica).
50% of patients with acute optic neuritis will develop MS.

Question 26

Papilloedema

Answer 26

Can sometimes see dilatation of the optic nerve sheath.

Question 27

Thyroid orbitopathy (6)

Answer 27

Seen in 1/4 of Graves cases, most common cause of exophthalmos.
Antibodies that activate TSH receptors also activate orbital fibroblasts and adipocytes.
Risk of compressive optic neruopathy.
Enlargement of ONLY MUSCLE BELLY (spares tendons, unlike pseudotumour)
NOT painful (unlike pseudotumour)
Order of involvement: Inferior rectus > Medial rectus > Superior rectus > Lateral rectus > Superior oblique