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Orbital Lesions
A- Vascular Abnormality
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Cavernous Sinus Thrombosis
: This refers to clotting within the cavernous
sinus, usually resulting from infection such as sinusitis, orbital or preseptal cellulitis or
otitis. There is a high mortality rate: 20% treated and up to 100% untreated. Features
are of rapid onset and may include severe headache, malaise, nausea and vomiting,
unilateral or often bilateral proptosis, chemosis, congestion of the facial, conjunctival
and retinal veins, reduced vision, and signs resulting from compromised function of
the third to sixth cranial nerves, which run through the cavernous sinus. Investigation:
is with imaging, especially MRI and MRI venography; systemic investigation for
infection is also performed, including lumbar puncture. Treatment: consists of
intravenous antibiotics and sometimes surgical drainage.
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Carotid–Cavernous Fistula:
Involves the development of an arteriovenous
fistula between the carotid artery and the venous cavernous sinus. Carotid–cavernous
fistulae are classified into ‘direct’ and ‘indirect’ forms.
* Direct fistulae are high-flow shunts in which carotid artery blood passes directly
into the cavernous sinus through a defect in the wall of the intracavernous portion of
the internal carotid artery as a result of trauma (75%), spontaneous rupture of an
intracavernous carotid aneurysm or an atherosclerotic artery.
Signs and Symptoms: may be days or weeks after head injury with a classic triad of
pulsatile proptosis (associated with a bruit and a thrill), conjunctival chemosis and a
whooshing noise in the head. Visual loss ( may be immediate due to ocular or optic
nerve damage at the time of head trauma or delayed visual loss that may occur as a
result of exposure keratopathy, secondary glaucoma, central retinal vein occlusion,
anterior segment ischemia or ischemic optic neuropathy), increased IOP due to
elevated episcleral venous pressure, ophthalmoplegia due to the ocular motor nerve
damage also may occur.
* Indirect fistula (Dural shunt), the intracavernous portion of the internal carotid
artery remains intact. Arterial blood flows through the meningeal branches of the
external or internal carotid arteries indirectly into the cavernous sinus, and the
clinical features are more subtle than in a direct fistula such that the condition may
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be overlooked. Spontaneous rupture of an atherosclerotic artery or of a congenital
malformation is the usual cause. Gradual onset of redness of one or both eyes is a
typical presentation, caused by conjunctival vascular engorgement. Ocular pulsation,
‘corkscrew’ epibulbar vessels, raised IOP, proptosis with bruit are mild if present and
ophthalmoplegia.
Investigation: CT and MRI ,Orbital Doppler imaging and angiography may show
abnormal flow patterns.
Treatment : Ocular complications may require specific measures in addition to
treatment of the fistula itself. Direct: Most carotid–cavernous fistulae are not life-
threatening, the organ at major risk is the eye. Surgery is indicated if spontaneous
closure does not occur. Treatment is likely to consist of a trans arterial approach to
repair the artery (e.g. coil) or occlude the involved sinus (e.g. coil, balloon, other).
Craniotomy for arterial repair is occasionally needed. Indirect, if required, treatment
usually involves trans venous occlusion of the involved sinus.
B- Cystic Lesions
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Dacryops:
is a frequently bilateral cyst of the lacrimal gland that developed from a
dilated obstructed duct. The possibility of a malignant tumor should always be
considered . Treatment involves excision or marsupialization, with histopathological
analysis.
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Dermoid Cyst:
is a choristoma (a mass of histologically normal tissue in an
abnormal location) derived from displacement of ectoderm to a subcutaneous
location. Dermoids are lined by keratinized stratified squamous epithelium (like skin),
have a fibrous wall and contain dermal appendages such as sweat glands, sebaceous
glands and hair follicles. It is one of the most frequently encountered orbital tumours
in children.
Signs & Symptoms: A superficial orbital dermoid cyst presents in infancy with a
painless firm round smooth non-tender mass 1–2 cm in diameter mobile under the
skin , most commonly located in the superotemporal part of the orbit ,the posterior
margins are easily palpable. A deep dermoid cyst presents in adolescence or adult life
with a gradually increasingly protruding eye (proptosis), dystopia, a mass lesion with
indistinct posterior margins or acutely with an inflamed orbit due to rupture.
Investigation: Imaging because some deep dermoids associated with bony defects
and may extend intracranially.
Treatment: Small lesions may be observed, putting in mind the possibility of rupture,
particularly from trauma.
Large dermoid treated by total excision taking care not to
rupture the lesion, since leaking of keratin into the surrounding tissue typically
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results in severe granulomatous inflammation. If incompletely excised, dermoids may
recur with persistent low-grade inflammation.
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Sinus Mucocoele:
A mucocoele develops when the drainage of normal
paranasal sinus secretions is obstructed due to infection, allergy, trauma, tumor or
congenital narrowing. A slowly expanding cystic accumulation of mucoid secretions
and epithelial debris develops and gradually erodes the bony walls of the sinus
causing symptoms by encroachment upon surrounding tissues. Orbital invasion
occurs usually from a frontal or ethmoidal mucocoele, . Presentation is in adult life
with proptosis , dystopia ,diplopia or epiphora. Pain is uncommon unless secondary
infection develops (mucopyocoele). Investigation: CT shows a soft tissue mass with
thinning or erosion of the bony walls of the sinus. Treatment involves complete
excision.
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Encephalocoele:
is formed by herniation of intracranial contents through a
congenital defect of the base of the skull, and can be located at the front or back of
the head. A meningocoele contains only dura whilst a meningoencephalocoele also
contains brain tissue. Presentation is usually during infancy. Pulsating proptosis may
occur due to communication with the subarachnoid space but, because the
communication is not vascular, there is neither a thrill nor a bruit. CT shows the bony
defect responsible for the herniation.
C- Vascular Tumors
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Varices:
consist of a plexus of thin walled distensible low-flow vein-like vessels.
Associations include Varices of the eyelids and conjunctiva. They commonly present at
any time from early childhood to late middle age as unilateral (most frequently is upper
nasal) intermittent non-pulsatile proptosis without a bruit. If there is free communication
with the normal circulation, reversible proptosis may be precipitated or accentuated by
increasing venous pressure through Valsalva manoeuvre. Imaging (e.g. MRI and magnetic
resonance venography (MRV), CT, ultrasound venography) shows a lobulated mass with
variable contrast enhancement, and may demonstrate phleboliths. Treatment ,Small
lesions generally do not require treatment. Surgical excision is technically difficult and
often incomplete because the lesions are friable and bleed easily; it can be complicated
by severe orbital haemorrhage and vascular optic nerve compromise.
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Lymphangioma:
is a rare hamartomatous vascular tumour that tends to enlarge
and infiltrate diffusely with time. Although usually isolated from the main circulation,
bleeding into the lumen may occur with subsequent formation of blood-filled
‘chocolate cysts’ that may regress spontaneously with time. Presentation is usually in
early childhood. Diagnosis: Anterior lesions typically manifest as several soft bluish
masses in the upper nasal quadrant, Posterior lesions may cause slowly progressive
proptosis, or initially may lie dormant and later present with the sudden onset of
painful proptosis secondary to spontaneous haemorrhage, which may be associated
with optic nerve compression . Treatment: In many cases the visual prognosis is good
without treatment, Surgical excision is difficult because lesions are unencapsulated,
friable, bleed easily and commonly infiltrate normal orbital tissues; repeated subtotal
excision may be necessary. Persistent sight threatening chocolate cysts can be drained
or removed sub-totally by laser.
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Capillary haemangioma:
is the most common tumour of the orbit in
childhood. Girls are affected more commonly than boys (3 : 1). It may present as a
small isolated lesion of minimal clinical significance, or as a large disfiguring mass that
can cause visual impairment and systemic complications.
Diagnosis: The lesion is usually noticed by the parent usually in the first few months of
life; approximately 30% are present at birth, superficial cutaneous lesions (‘strawberry
naevi’) are bright red, preseptal (deeper) tumours appear dark blue or purple through
the overlying skin and are most frequently located superiorly, but both pulsation and a
bruit are absent. Deep orbital tumours give rise to unilateral proptosis without skin
discoloration. Investigation: Imaging (Ultrasound, MRI or CT)is generally performed for
other than very small lesions.
Treatment: is indicated principally for amblyopia secondary to induced astigmatism,
anisometropia or strabismus, and less commonly for cosmesis, optic nerve
compression or exposure keratopathy. Beta-blockers (Oral propranolol) is now widely
used. Steroids: Injection into a cutaneous or preseptal tumour is usually effective in
early lesions (complications include CRAO, skin depigmentation, necrosis fat atrophy
and systemic effects such as adrenal suppression. Topical high-potency steroids are
sometimes appropriate. Systemic steroids administered daily over several weeks may
be used. Laser may be used to close blood vessels in superficial skin lesions less than 2
mm in thickness. Local resection with cutting cautery or laser may reduce the bulk of
an anterior circumscribed tumour but is usually reserved for the late inactive stage
unless a resistant tumour is sight- or life-threatening.
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Cavernous Haemangioma:
occurs in middle-aged adults, with a female
preponderance of 70%; growth may be accelerated by pregnancy.It is the most
common orbital tumour in adults.
Signs & Symptoms: Slowly progressive unilateral axial proptosis which may be
associated with optic disc oedema and choroidal folds; bilateral cases are very rare.
Investigation: CT and MRI show a well circumscribed oval lesion, usually within the
muscle cone.
Treatment: Many cavernous haemangiomas are detected by chance on scans
performed for unrelated reasons and observation alone is often appropriate.
Symptomatic lesions require surgical excision because they gradually enlarge. The
cavernous haemangioma is usually well encapsulated and relatively easy to remove.
D- Lacrimal Gland Tumors
1- Pleomorphic adenoma
(benign mixed-cell tumour) is the most common
epithelial tumour of the lacrimal gland. Young to middle-aged adults are the
predominantly affected group.
Symptoms & Signs : Painless slowly progressive proptosis or swelling in the
superolateral eyelid, usually of more than a year duration. Orbital lobe tumour
presents as a smooth, firm, non-tender mass in the lacrimal gland fossa with
inferonasal dystopia. Palpebral lobe tumour is less common and tends to grow
anteriorly causing upper lid swelling without dystopia. Investigation: CT shows a round
or oval mass, with a smooth outline and indentation but not destruction of the
lacrimal gland fossa.
Treatment involves surgical excision. If the diagnosis is strongly suspected, it is wise to
avoid prior biopsy to prevent tumour seeding into adjacent orbital tissue. Incomplete
excision or preliminary incisional biopsy may result in seeding of the tumour into
adjacent tissues, with recurrence and occasionally malignant changes.
2- Lacrimal gland carcinoma:
is a tumour that carries a high morbidity and
mortality. The peak incidence is in middle-aged adults. Tumour may presents after
incomplete excision of a benign pleomorphic adenoma with eventual malignant
transformation or without a previous history of a pleomorphic adenoma as a rapidly
growing lacrimal gland mass, usually of several months duration. Symptoms & signs:
The history is short. Pain is a frequent feature of malignancy. A mass in the lacrimal
area causing inferonasal dystopia. Posterior extension may give rise to proptosis,
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ophthalmoplegia , optic disc swelling and choroidal folds. Investigation: CT shows a
globular lesion with irregular serrated edges, often with contiguous erosion or invasion
of bone.
Biopsy is necessary to establish the histological diagnosis.
Treatment: involves excision of the tumour and adjacent tissues. Extensive tumours
may require orbital exenteration or midfacial resection, but the prognosis for life is
frequently poor. Radiotherapy combined with local resection may prolong life and
reduce pain.
E- Neural Tumors
1- Optic nerve glioma
is a slowly growing astrocytoma that typically affects
children (median age 6.5 years). The prognosis is variable; some have an indolent
course with little growth, while others may extend intracranially and threaten life.
Symptoms & signs: Slowly progressive visual loss and proptosis. The optic nerve head,
initially swollen, subsequently becomes atrophic. Intracranial spread to the chiasm and
hypothalamus may develop. Investigation: MRI effectively demonstrates the tumour,
and may show intracranial extension if present.
Treatment: As the tumour is intrinsic to the optic nerve, resection means that all vision
will be lost in the operated eye. Observation may be considered in patients with a
typical tumor on imaging in whom the tumour is confined to the orbit, especially if
there is good vision and no significant cosmetic impairment. Surgical excision with
preservation of the globe is indicated in those with large or growing tumours where
complete resection of the tumour can be achieved, particularly if vision is poor and
proptosis significant. Radiotherapy may be combined with chemotherapy for tumours
with extension that precludes complete surgical excision.
2- Optic nerve sheath meningioma
: is a benign tumour of the optic nerve.
Typically affect middle-aged women. The prognosis for life is good in adults, although
the tumour may be more aggressive in children in whom 25% occur.
Symptoms & Signs: typically consist of gradual visual impairment in one eye, transient
obscurations of vision may occur. The usual sequence of involvement is: *Optic nerve
dysfunction and chronic disc swelling followed by atrophy, *Opticociliary collaterals
(30%), *Restrictive motility defects, particularly in upgaze , *Proptosis.
Investigation: MRI is the investigation of choice, CT shows thickening and calcification
of the optic nerve.
Treatment may not be indicated in a middle-aged patient with a slowly growing lesion,
but excision is required for an aggressive tumour, particularly if the eye is blind or
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there is a risk of intracranial extension. Radiotherapy may be appropriate as a vision-
sparing approach, or as adjunctive treatment following surgery.
F- Lymphoma
:
The majority of orbital lymphomas are non-Hodgkin, and most of
these (80%) are of B-cell origin. Those affected are typically older individuals.
Symptoms & Signs: An absence of symptoms is common, but may include discomfort,
double vision, a bulging eye or a visible mass. Anterior lesions may be palpated, and
generally have a rubbery consistency. Local lymph nodes should be palpated, but
systemic evaluation by an appropriate specialist is required.
Investigation: Orbital imaging, usually with MRI, Biopsy is usually performed to establish
the diagnosis. Systemic investigation to establish the extent of disease .
Treatment: Radiotherapy is used for localized lesions, and chemotherapy for
disseminated disease, Immunotherapy is a newer modality and occasionally a well-
defined orbital lesion may be resected.
G- Rhabdomyosarcoma:
is the most common primary orbital malignancy in
children; 90% occur in children under 16 and the average age of onset is 7 years. Four
subtypes are recognized: Embryonal, Alveolar, Botyroid and pleomorphic.
Symptoms & Signs: Rapidly progressive unilateral proptosis is usual and may mimic an
inflammatory condition such as orbital cellulitis. Swelling and redness of overlying skin
develop but the skin is not warm, Diplopia is frequent, but pain is less common.
Investigation: MRI & CT shows a poorly defined mass with adjacent bony destruction,
incisional biopsy is performed to confirm the diagnosis and systemic investigation for
metastasis should be performed; the most common sites are lung and bone.
Treatment: combination of radiotherapy, chemotherapy and sometimes surgical
debulking. The prognosis for patients with disease confined to the orbit is good.
H- Orbital Metastatic Tumours
1- Adult Metastatic Tumours:
the most common primary sites are
breast, bronchus, prostate, skin (melanoma), gastrointestinal tract and kidney.
2- Childhood Metastatic Tumours:
Neuroblastoma, Myeloid sarcoma
and Langerhans cell histiocytosis.
3- Orbital invasion from adjacent structures:
Sinus tumours,
Bony invasion, Orbital invasion from eyelid, conjunctival and intraocular tumours.