H&N- Orbit

Question 1

Coat’s disease imaging findings

Answer 1

Clue: Unilateral, microphthalmia, subretinal exudate, retinal detachment, no extraocular findings.

CT: Unilateral microphthalmia.
within globe (exudate)
Uncommon Ca+
MR: hyper both T1 and T2 (due to proteinaceous and haemorrhagic content)
T1 C+: subfoveal enhancing nodules, intraretinal macrocysts, nerve enhancement if advanced.
US: Linear detached retina, tiny cholesterol crystals

Question 2

Coat’s path/demographics

Answer 2

Dx within 1st decade of life.
Slightly male predominance.
Breakdown of blood-retinal endothelial barrier, development of telangiectasia, leading to subrtinal exudate of lipoprotein exudate.
Usually isolated.
Rarely bilateral, associated with genetic syndromes: Norrie disease (X-linked recessive mutation), familial exudative vitreoretinopathy (X linked recessive and autosomal variants), Coats Plus (skeletal defects, growth failure, movement disorder, seizure)

Question 3

Ocular metastasis:
-Most common site?
-Primary ?
-Appearance in imaging

Answer 3

Common site: choroid (due to high vascularity)
Primary: Carcinomas (breast and lung)
Appearance: solid irregular enhancing mass with brad base on choroid.

Question 4

Retrolental fiboplasia (Retinopathy of prematurity)
-pathophysiology
-Appearance in imaging

Answer 4

-Occurs due to prolonged exposure to supplemental oxygen in premature infants which interrupts normal vasculogenesis and leads to incomplete vascularisation of the retina.
-Bilateral microphthalmia, retinal detachment, hyperdense globes. May be associated with haemorrhage.
Calcifications rare (except in advance stages).

Question 5

Most common childhood soft tissue soft tissue sarcoma?

Answer 5

Rhabdomyosarcoma.

Question 6

Most common benign orbital mass in childhood?

Answer 6

Desmoid

Question 7

Age of presentation or rhabdomyoscaroma?

Answer 7

Most of them (70%) <12 years.
Les frequently (40%) < 5 years.

Question 8

Describe histological subtypes of rhabdomyosarcomas

Answer 8

4 histological subtypes:
-Embryonal RMS (50%): most common, young children (mutation in 11p15locus). 70-90% affecting H&N or genitourinary tract.
(BOTRYOIDES variant: typically in 2-5 years of age, develops in the walls of hollow, mucosal lined structures such as nasopharynx, common bile duct, bladder and vagina. Has the most favourable prognosis)
-Alveolar RMS (20%): 2nd most common; 15-25 years, adolescence. Most common in extremities and trunk. 50% have FOX01 to PAX3 (or PAX7) gene fusion (better prognosis)
-Pleomorphic RMS (20%): Least common; 40-60 years. Adults. Extremities (rarely in H&N). Often fatal.
-Spindele cell/sclerosing (10%): affects all ages.

Question 9

Epidemiology of rhabdomyosarcoma

Answer 9

-Most common childhood soft tissue sarcoma (most common extra ocular orbital malignancy)
-Age presentation < 12 years (70%) / < 5 years (40%).
-Most common in Caucasian.
-40-50% occur in H&N (most commonly in orbit, sinus (parameningeal sites, and other)), genitourinary tract (25%), extremities (15%), other (10%)

Question 10

Frequent sites of affection of rhabdomyosarcoma

Answer 10

40-50% H&N
25% genitourinary (bladder, vagina, prostate)
15% extremity
10% other (common bile duct)

Question 11

Associations of rhabdomyosarcoma

Answer 11

Increase incidence of RMS in Noonan syndrome, neurofibromatosis type 1, Li-Fraumeni, Beckwith-Wiedemann, hereditary retinoblastoma. May occur as radiotion-induced 2nd primary neoplasm.

Question 12

Complications of rhabdomyosarcoma

Answer 12

Intracranial extension (up to 50%)
Perineural spread
Metastasis (20%) to lungs and bone marrow.

Question 13

Diagnosis clue for rhabdomyosarcoma

Answer 13

Clue: invasive soft tissue mass with variable enhancement.
* CT: Invasive soft tissue mass with variable enhancement
Osseous erosion common but not seen in all cases (in 20%)
* MR: T2FS, Stir: Isointense T1, hyperintense T2 signal relative to muscle (Not “fluid bright” unless necrotic/cystic components)
T1 C+ FS: Variable contrast enhancement, often mild to moderate (Diffuse, intense enhancement atypical)
Often restricts diffusion
* PET/CT: hypermetabolic (improve staging and posttreatment evaluation).

Question 14

Most common primary intraocular neoplasm in childhood

Answer 14

Retinoblastoma

Question 15

Path behind retinoblastoma (genetics)

Answer 15

Mutation of the retinoblastoma gene (tumor suppressor gene in Ch13)(lack of both alleles)

Question 16

Describe incidence of bilateral vs unilateral retinoblastoma and genetic background

Answer 16

Unilateral = 60%. Sporadic somatic mutation of both alleles of RB1.
Bilateral= 40%. AD, involves a hereditary germinal mutation of RB1 + sporadic mutation of the other copy.

Question 17

CT appearance of retinoblastoma

Answer 17

> 90% presents calcium deposits within irregularly thickened retina.
Heterogeneous post contrast enhancement.

Question 18

MR appearance of retinoblastoma

Answer 18

T1 slightly hyper to vitreous
T2 slightly hypo to vitreous.
Post con: heterogeneous enhancement

Question 19

Associations when bilateral retinoblastoma

Answer 19

-Trilateral: bilateral RB +mid line intracranial tumor (pineal tumor)
-Quadrilateral: bilateral RB + mid line intracranial tumor +/- suprasellar tumor
-All of them at reisk of other germ line malignancies: SARCOMA, melanoma, CNS tumor, epithelial (lung, bladder, breast)

Question 20

Growth morphology of retinoblastoma

Answer 20

-Endophytic 45%, inwards protrusion into vitreous
-Exophytic, 45%, outwards into subretinal space, associated with retinal detachment and subretinal exudate.
-Mixed 10%
-Diffused infiltrating form (rare), plaque like growth, often no Ca+

Question 21

Invasion rout of retinoblastomas

Answer 21

Extraocular extension in < 10% of cases :
-choroidal invasion: localized thickened and heterogeneous contrast enhancement near tumor
-Scleral invasion: interruption in thin, hypointense zone surrounding enhancing choroid.
-Optic nerve invasion: thickening of optic disk (prelaminar), enhancement of nerve (post laminar)

Question 22

Diagnostic methods of retinoblastoma

Answer 22

-Opthalmoscopy
-Ultrasound (A and B scan)
-CT (Ca+)
-MR (mapping and prognostication)

Question 23

Differential diagnosis of retinoblastoma

Answer 23

-Persistent hyperplastic primary vitreous
-Coat’s disease
-Toxocariasis
-Retinopathy of prematurity
-Coloboma
-Other causes of leucocoria (retinal detachment)

Question 24

Most common retinal pathologies?

Answer 24

Retinoblastoma (childhood)
Hemangioblastoma (adult)
Detachment (diabetic retinopathy)

Question 25

Most common choroid pathologies?

Answer 25

Melanoma
Metastases (since it is the most vascular structure in the eye)
Detachment.

Question 26

Most common sclera pathologies

Answer 26

Infection
Pseudotumour
Detachment

Question 27

Path of Persistent hyperplastic primary vitrous

Answer 27

Congenital developmental malformation due to incomplete/failure of hyaloid regression, causing remnant to persist in Cloquet canal (should involute by 8th months)
Most cases isolated and sporadic 80%
Dominance and recessive forms described.

Question 28

Associations and complications of Persistent hyperplastic primary vitrous

Answer 28

-Usually isolated (90%)
-When bilateral, could be associated with systemic or syndromic conditions (Norrie, Walker Warburg, T13), perinatal infection (congenital cMV and rubella) methabolic (maternal cocaine abuse)

-Complications: retinal detachment, glaucoma .

Question 29

Morphology of Persistent hyperplastic primary vitous

Answer 29

-Retrolental soft tissue and stalk with martini glass shape of enhancing soft tissue (triangular retrolental vascular tissue + central stalk of hyaloid remnant)
-Location: 50-80% mixed anterior and posterior/ 15-25% isolated posterior form / 5-20% isolated anterior form/
-Unilateral (90%) > bilateral (10%)

Question 30

Diagnostic modalities for PHPV

Answer 30

CT: Small globe, linear retrolental density &/or vitreous hemorrhage, retinal detachment. Calcification rare

MR: -Retrolental martini glass-shaped enhancing soft tissue.
-Small globe, vitreous abnormally hyperintense on both T1WI and T2WI
-Hemorrhage and layering debris in vitreous &/or retinal detachment common (signal depends on age of blood)

US: -Lens displacement, hyperechoic retrolental stalk
- Thickened hyaloid seen as double line at pars plana

Question 31

What is coloboma?
Associations?
Diagnostic features?
Most important Diferential diagnosis?

Answer 31

-Congenital defect caused by failure of closure/fusion of fetal optic fissure. Appears as outpouching of the optic tissue (retina, choroid, sclera,iris). Most frequently INFERO NASAL location.

-If bilateral, suspect syndromic associations: CHARGE, T13, T18, VACTER etc)

-Dx: Isodense/isointense to vitreous on CT and MR.
Sclera enhances post contrast.
Ca+ rare (only when chronic, and at margins)

-DD: Staphyloma: focal outpouching due to thinning and stretching of scleral-uveal (outer) layer of globe.
Posterior types are the most common, off centered more TEMPORAL to optic nerve.

Question 32

Causes of leukocoria

Answer 32

-Neoplastic
Retinoblastoma (<3 years, Ca+)
Ocular melanoma
-Acquired:
Retinal detachment
Retinoplasty of prematurity
Coloboma
-Infection: Toxocariasis
-Congenital:
Congenital cataract
Persistent Hyperplastic Primary Vitrous
Coat’s disease

Question 33

Retinal detachment
-Cause
-Clinical presentation
-Physiopath
-Diagnostic features

Answer 33

-Cause: Trauma, Traction (DM), exudative (neoplasia)

-Clinical presentation: Reduced visual acuity, floaters, flashes, visual field loss

-Physiopath: Separation of the inner neurosensory retina from the outer pigmented epithelial layer. Fluid in subretinal space.

-Dx features:
Detached retina demonstrates aftermovements
Limited anteriorly by ora serrata
Converges posteriorly on optic disc

Question 34

Choroidal detachment:
-Cause
-Clinical presentation
-Physiopath
-Diagnostic features

Answer 34

-Cause: Increased intraocular pressure (transudative effusion due to trauma, exudative effusion due to infection or inflammation), haemorrhage, other (valsalva, hypertension, neoplasm, caroticocavernous fistula)

-Clinical presentation: Dull to severe pain

-Physiopath: detachment of the choroid from the underlying sclera. Fluid in suprachoroidal space

-Dx features:
NO aftermovements of the detached membrane
NOT limited anteriorly by ora serrata
Diverges from optic disc posteriorly

Question 35

Lens dislocation:
-Cause
-Clinical presentation
-Physiopath
-Diagnostic features

Answer 35

Cause:
-Trauma is the most common cause.
-Non traumatic: Marfan syndrome (typically upwards and out), homocystinuria (typically downwards), Weil-Marchesani syndrome, Ehlers-Danlos. Hereditary. Infective (syphilis)

Clinical presentation: History of trauma, or reduced visual acuity

Physiopath: Subluxation or dislocation of the lens.

Dx features:
-Subluxation: Unilateral deviation of lens margin posteriorly into vitreous body. Contralateral margin fixed adjacent to iris.
-Complete dislocation: lens in dependent position in the vitreous.
Free mobility with eye movements.

Question 36

Subtypes of Optic Pathway Glioma
Histopath
Epidemio
Dx pearls

Answer 36

Most common in childhood (>90%) less than 20yo. (most common onset 10yo)

-Childhood syndromic to NF1 (30-40%)
Low grade gliomas (pilocytic astrocytoma/ fibrillary astrocytoma).
Irregular, buckling and kinking.
Anterior pathways.
T1 peripheral hyperintensity (perinerual arachnoid gliomatosis)

-Childhood sporadic
Low grade gliomas (pilocytic astrocytoma/ fibrillary astrocytoma)
Fusiform. Cystic changes.
Posterior pathways, including chiasm.

-Adult type.
High grade gliomas (GBM)
ON and sheath, posterior spread.

Question 37

Main differential diagnosis with optic sheath meningioma?

Answer 37

Optic Pathway Glioma:
-Variable enhancement
-no Ca+
-Irregular ON itself

Opthic sheath meningioma:
-Uniform enhancement
-Usually Ca+ in 1/3 to 1/2 of the cases.
-Mass is surrounding ON.
-Characteristic perioptic cyst (entrapped CNS)

Question 38

Path of capillary haemangioma of infancy and childhood?

Answer 38

-Proliferation of vascular endothelium: cellular hyperplasia.

-Genetics: Most cases sporadic.
Small percent AD (Ch 5)

-Immunohistochemical marker GLUT1 positive in all phases

-Micro: Unencapsulated, lobulated cellular neoplasm. Thin walled capillaries with scant stroma.

Question 39

Phases of capillary haemangioma of infancy and childhood

Answer 39

3 distinct phases (initially increase in size but eventually regress spontaneously)
Proliferative phase: Appears few weeks after birth and grows rapidly for year 1 or 2
Involuting phase: Regression over 3-5 years
Involuted phase: Complete regression by late childhood

Question 40

Clinical presentation of capillary haemangioma of infancy and childhood?

Location?

Answer 40

NOT present at birth.
Appear within 1st few weeks.
Slight F predominance.

Preseptal: Predilection of eyelids, supranasal periorbital. Orbital involvement: typically superficial superomedial extraconal location.
May extend postseptal, into superior orbital fissure or intraconal space
Exclusively retrobulbar in 10%

Question 41

Associations of capillary haemangioma of infancy and childhood?

Answer 41

Rarely associated with genetic syndromes.

PHACES syndrome (posterior fossa anomalies, hemangioma, arterial, cardiac, eye andsternal anomalies)

Question 42

Dx of capillary haemangioma of infancy and childhood?

Answer 42

Generally:
-Proliferative phase: prominent vessels.
-Involution: increase fat and septation. Decreased enhancement.
-NO Ca+

CT: Lobular, intermediate or slightly hyperdense, homogeneous.
Intense homogeneous enhancement

MR: Best for mapping large, deep lesions.
T1 intermediate to to muscle ; prominent internal flow voids
T2: Moderate hyperintensity (high cellularity)
T1 C: intense enhancement.
MRA: Helpful for assessing arterial abnormalities, spetially in PHACES syndrome.

US: lobulated soft tissue mass. High vessel density, absent arteriovenous shunting, high peak arterial Doppler shift
When superficial, US confirms clinical diagnosis

Angio: Enlarged feeding branches (from external carotid, ophthalmic arteries)

Question 43

Most common intraconal mass in adult?

Answer 43

Venous Cavernous malformation

Question 44

Diagnostic feature of cavernous venous malformation?

Answer 44

-Well-demarcated, ovoid, enhancing intraconal mass
-Avid dynamic enhancement
(Early: Heterogeneous, patchy central enhancement;
venous phase: Diffuse enhancement;
Delayed phase: Fills in homogeneously)
-Benign remodeling of bone in larger lesions
-Phleboliths are pathognomonic.

T1: iso to muscle
T2: hyperintense. Hypodense rim (pseudocapsule)
DWI: restriction with mean ADC values ranging from 1.23-1.39 x 10⁻³ mm²/s

US: Well-demarcated hyperechoic retrobulbar mass. Highly reflective borders representing pseudocapsule. Medium to high internal reflectivity representing multiple vascular channels.

Angio: Contrast puddles extending into late venous phase. No distinct tumor blush. No large feeding vessel.

NM: SPECT shows delayed focal uptake on Tc-99m RBC scintigraphy

Question 45

Path of venous cavernouse malformation:

Answer 45

Slowly growing vascular malformation.
Classified as slow-flow venous lesion with dilated vascular space.
No evidence of cellular proliferation
Pseudo encapsulated by compressed surrounding tissue

Question 46

Main DD betwen venous cavernous malformation and capillary haemangioma of infancy and childhood?

Answer 46

Cavernous venous malformation:
-Pseudocapsule of compressed surrounding tissue
-Usually lateral
-Mostly intraconal
-Characteristic dynamic enhancement
-Slow-flow venous lesion.
-No cellular proliferation
-No GLUT 1 marker

Capillary haemangiomas of infancy and childhood:
-Non encapsulated
-Usually superomedial
-Mostly extraconal and superficial
-Monophasic enhancement pattern. Flow voids.
-Thin walled capillary-like vascular spaces
-Cellular proliferation
-marker GLUT1 positive in all phases

Question 47

Causes of optic neuritis?

Answer 47

Multiple causes:
-Isolated (idiophatic)
-Non-infective: Multiple sclerosis is the most common cause (40-60% of patients will develop MS. 70-90% of MS will develop ON). Neuromyelitis optica spectrum (NMO such as Devic), sarcoidosis, LES, ADEM, Behcet, Sjogren, anti-MOG, CRION
-Infective: viral neuritis (herpes, varicella, HIV), radiation, Lyme disease, Toxo.
-Paediatric: rare, may follow viral or vaccination, ADEM.

Question 48

Epidemiology of optic neuritis? (patient profile)
Clinical presentation?
Prognosis?
Treatment?

Answer 48

Young adult (35yo average), more common in female. Caucasian.

Acute onset. Pain (90%), worsen with eye movement. Visual loss.

Spontaneous recovery of visioncharacteristic of MS (ON frequently initial demyelinating event in MS)
Recurrent ON is common (Overall 35%, seen in MS, NMOSD, anti-MOG)
Recurs in same eye in 20-30%

Treatment: Dependent on etiology.
Medical: Steroids, immunomodulatory therapy.

Question 49

Imaging diagnosis for optic neuritis

Answer 49

CT often normal.

T1: Optic nerve diffuse enhancement
T2/FLAIR/STIR: Focal or segmental T2 hyperintensity of optic nerve
T1 C+: Central or diffuse optic nerve enhancement (active demyelination)
DWI: increased diffusivity (Related to disruption of myelinated axons. Differentiates acute ON from ischemic optic neuropathy)

US: Enlargement of ON. Elevated peak systolic & end diastolic arterial velocities

Optical coherence tomography (OCT): Decreased retinal nerve fiber layer thickness

Question 50

Definition and characteristics of orbital venous varix

Answer 50

Low-flow venous malformation,
with systemic venous connection,
dynamically distensible varix

Question 51

Epidemiology of orbital venous varix (classificatoin depending on origin)

Answer 51

Two origins:
-Primary: congenital vascular malformation with slow flow, distensible component, & systemic venous connection.
-Secondary acquired: in association with dural arteriovenous (AV) fistula, cavernous carotid (CC) fistula or intracranial AV malformation (AVM)

Question 52

Clinical presentation of orbital venous varix

Answer 52

Any age. F=M.
- Intermittent, reversible proptosis (proptosis casused by change in head position or Valsalva)
- Variable pain & ophthalmoplegia
- Sudden worsening due to thrombosis or hemorrhage

Question 53

Associations of orbital venous varix

Answer 53

May co-exist with lymphatic malformations.

Question 54

Morphology of orbital venous varix

Answer 54

Well-defined margins but may have irregular or lobulated contours; often tubular or tortuous
-Location: May occur anywhere in orbit; usually retrobulbar & extraconal, often superolateral
-Size changes dynamically with venous pressure Valsalva (stress proptosis)

Question 55

Diagnostic features of orbital venous varix

Answer 55

Best clue: Intensely enhancing orbital mass that distends with ↑ venous pressure
Best imaging tool: Dynamic CT with provocation maneuver
MR is preferred if haemorrhage or thrombosis is suspected.

-NECT: Well-defined, tubular or tortuous soft tissue density lesion in retrobulbar space; may contain phleboliths
CECT: Intense enhancement; ↑ in size on Valsalva
-MR: T1WI & T2WI: Complex signal, blood products, fluid levels
T1WI C+: Intense enhancing orbital mass that distends with ↑ venous pressure
Variable areas of non enhancement:
Heterogeneous fast or turbulent flow void
Areas of thrombosis or acute hemorrhage
Cystic or lymphatic spaces
-US: Hypoechoic; slow flow on Doppler; dynamically ↑ with Valsalva; circumscribed & mass-like when thrombosed
-Angio: Late venous phase: Filling of dilated structure
Systemic venous connection

Question 56

Definition of thyroid ophthalmopathy

Answer 56

Autoimmune orbital inflammatory condition associated with thyroid dysfunction

Question 57

Epidemiology and clinical presentation of thyroid ophthalmopathy

Answer 57

Most common cause of painless proptosis.
Visual loss secondary to compression.
Middle-age adults aged 30-50yo. F»M.

Question 58

Complication of thyroid ophthalmopathy

Answer 58

Compressive optic neuropathy leading to visual loss.

Question 59

Imaging features of thyroid ophthalmopathy

Answer 59

Enlargement of EOM:
Fusiform enlargement of muscle belly
Sparing of tendinous insertions (DD with pseudotumor and other)
Mutiple muscle affected&raquo_space; single EOM affected
“I > M > S > L > O” (if O and L affected, unlikely due to thyroidal disease)
Bilateral 85%. Symetrical 70%.
Expansion of orbital fat (deposition of GAG in orbital fat)
Straightened optic nerves.

CT: isodense. Internal lower density indicates GAG deposition.
C+ superior ophthalmic vein enlargement.

MRI: T1: isointense. Decreased ON diameter.
T2 /STIR muscle with acute disease (oedema and inflammation). retro-orbital fat.
muscle could be due to fibrosis.
T1 C+: Decreased enhancement (impaired microcirculation)

NM: DTPA and somatostatin analogues: Retrobulbar uptakes (active inflammation)
(decreases with immunosuppressive therapy)

Question 60

Most common painful mass in adults?

Answer 60

Orbital pseudotumor

Question 61

Epidemiology of orbital pseudotumor and clinical presentation?

Answer 61

Most common painful orbital mass in adults
3rd most common orbital disorder (After thyroid and lymphoproliferative lesions)

Risk factors include low socioeconomic status, elevated BMI, and bisphosphonate therapy

Presentation: Acute to subacute orbital pain, swelling, restricted motion, diplopia, proptosis, and impaired vision.
Any age, mean 5th decade.
Myositic form F>M

Question 62

Path of orbital pseudotumor
Histologic variants

Answer 62

Polymorphous chronic inflammation and fibrosis
Plasma cell infiltrate with IgG4 variant

Histologic variants:
Sclerosing: Disproportionate connective tissue and early fibrosis with sclerosis
Granulomatous: Histiocytes, multinucleated giant cells, and granuloma formation
Vasculitic: Small vessel inflammatory infiltrate
Eosinophilic: Infiltration of eosinophilia without vasculitis; more common in children

Question 63

Disease variants for orbital pseudotumor

Answer 63

Tolosa-Hunt: Orbital apex into cavernous sinus
Lymphocytic hypophysitis: enlarged pituitary stalk in postpartum/ 3rd trimester woman. T2 dark rim.
Sclerosing: More often bilateral, may extend into sinuses, chronic progressive fibrosis.

Question 64

Associations of orbital pseudotumor

Answer 64

Other Autoimmune disorders: Crohn disease, systemic lupus, rheumatoid arthritis, type I diabetes, myasthenia gravis, ankylosing spondylitis, Churg-Strauss syndrome

Question 65

Complications of orbital pseudoturmo

Answer 65

Secondary angle-closure glaucoma

Question 66

Lesion morphology of orbital pseudotumor
Areas of involvement

Answer 66

General morphology:
May be focally mass-like or diffuse
Irregular margins, infiltrative features
May mimic neoplasm or infection
Enhancing inflammatory tissue
Causes enlargement, and enhancement of involved structures
Typically unilateral (bilateral in ~25% cases, common in children)

Area of involvement: any area of orbit:
-Lacrimal (lacrimal gland- dacryoadenitis)
most common pattern (~ 20% overall)
Diffuse enlargement of 1 or both
Cannot differentiate from lymphoproliferative lesions or sarcoidosis by imaging alone

-Myositic (extraocular muscles)
2nd most common pattern
Any muscle affected; lateral rectus and superior complex most frequent
Involves tendinous insertions (unlike thyroid disease), tubular configuration, shaggy margins

-Anterior (globe, retrobulbar orbit)
3rd most common pattern
Uveal-scleral (episcleritis or sclerotenonitis): Thickened sclera with shaggy enhancement
Variable retrobulbar fat, optic nerve and sheath involvement
Perineuritis (uncommon): Irregular nerve sheath thickening and enhancement; differentiate from optic neuritis

-Diffuse (multifocal intraconal ± extraconal)
Overlaps with other patterns
Often mass-like; tends not to distort globe or erode bone

-Apical (orbital apex, intracranial extension)
Less common; involves orbital apex with posterior extension through fissures

Question 67

Image diagnostic clue:

Answer 67

Best clue: Poorly marginated, mass-like, enhancing inflammatory soft tissue involving any area of orbit
CT: Multifocal or infiltrative soft tissue
May rarely remodel or erode bone
CECT: Dynamic CT: Attenuation ↑ into late phase
(Differentiates from lymphoma → attenuation decreases)

MR: T1:
T2/STIR hypointense due to cellular infiltrate and fibrosis (Particularly in chronic or sclerosing variants)
DWI: Higher ADC favors pseudotumor, while lower ADC suggests lymphoproliferative disorder, but overlap exists
T1 C+: enhancement.
MRA: Tolosa-Hunt: Associated with cavernous internal carotid artery (ICA) narrowing that reverses with effective therapy

Best imaging tool: Enhanced MR with fat suppression
Diagnosis of exclusion.
Consider infectious cellulitis and carotid fistula if acute onset
Consider other systemic causes with bilateral, multifocal, lacrimal, or apical involvement
Atypical onset, poor response, or recurrence should prompt biopsy to confirm and exclude lymphoma

Question 68

Most important differential diagnosis of orbital infiltrative disease

Answer 68

-Idiopathic Orbital pseudotumor (acute onset, painfull. T2/STIR hypointense due to cellular infiltrate and fibrosis. Multispacial )

-Lymphoproliferative lesions (main DD, biopsy should be considered to exclude lymphoma. Solid modelling tumor. predilection for lacrimal gland, eyelid, conjunctiva, eyelid, extraconal orbit. T2 Hyper)

-Thyroid ophthalmopathy (painless, extraocular muscle belly, thyroid dysfunction)

-Sarcoidosis (painless. Anywhere in orbit. Uveitis specially anterior is most common ocular manifestation. Similar predilection to lacrimal glands, bilateral. Optic nerve sheath involvement. EOM involvement asymmetric. Presental infiltration.)

-Granulomatosis with polyangitis Wegener (Necrotizing vasculitis of multiple organs, Particularly renal and respiratory. Paranasal sinus and orbital involvement with bone destruction; commonly bilateral)

-IgG4 (Considered systemic disease with multiorgan involvement. Any part of orbit may be involved with predilection for lacrimal gland and trigeminal nerve, dura-arachnoid IgG4 related hypertrophic pachymeningitis, pituitary gland stalk Hypophysitis. Adjacent paranasal sinus inflammation common. Increased serum IgG4(+) concentration in 60-70% of patients. Histology shows lymphoplasmacytic infiltration of IgG4(+) plasma cells and lymphocytes with storiform fibrosis
Steroid responsive)

-Orbital cellulitis

Question 69

Basal cell carcinoma
Epidemiology
Where does it affect the most in H&N?
Where does it metastasize?
Clinical expression types?
Clinical presentation?
Pathogenesis
Risk factors?

Answer 69

Elderly, 7-8th decade, fair skinned.

Mainly affecting lower eyelid and medial cantus.

Rarely metastasizes.

Clinically: sporadic or part of a genetic syndrome (basal cell nevus syndrome or Gorlin Goltz)

Presentation: indolent, progressive locally aggressive and disfiguring, prevents eyelids to close. Leads to corneal lesion.

Pathogenesis: mutation in PTCH tumor supresor gene leading to activation of hedgehog signalling pathway.
Sporadic: 30% associated with mutation.
Genetic: germline loss + acquired loss .

Risk factors: Sun exposure, fari skinned, elderly, immunosuppression and disorders of DNA repair.

Question 70

Basal Cell nevus syndrome (Gorlin Goltz) syndrome findings

Answer 70

Manifestation <20yo.
Multiple basal cell Ca.
Medulloblastoma.
Ovarian fibromas
Odontogenic keratocysts
Pits of the palms and soles
Developmental abnormalities.

Question 71

Most common lacrimal gland benign neoplasm
Clinical presentation and epidemiology?
Complication?

Answer 71

Benign mixed tumor (aka pleomorphic adenoma) (~90% of benign tumors) (~ 50% primary epithelial tumors)

Presentation: slow growing mass, painless, proptosis (inferomedial displacement).
Young adults 2-5th decade.

Complication: malignant transformation with low cumulative risk.

Question 72

Best diagnostic clue for benign mixed tumor of the lacrimal gland?

Answer 72

Unilateral, well defined solid mass.
30% Ca+. Common to see small cysts.
Bony scalloping/remodeling.
Moderately enhancing.
T1 hypo. T2 hyper.

Question 73

Most common malignant tumor of the lacrimal gland?
Complication?

Answer 73

Adenocystic carcinoma (accounting for 50% of the maignant tumors)

Complication: peri-nerual spread

Question 74

Best diagnostic clue for adenocystic carcinoma of h&N?

Answer 74

Unilateral, ill defined solid mass.
Bony erosion 70%
Ca+ 20%
Wedge or tail sign