The Orbits

10.1055/b-0034-87897

The Orbits

**Table 4.24 Small orbit**
Diagnosis	Findings	Comments
Anophthalmia/microphthalmia	CT/MRI: proportionate decrease in size of orbit on all imaging modalities. Absent ocular tissue in anopthalmia. Small complete globe in simple microphthalmia; small abnormal globe with coloboma in complex micropthalmia. Globe size abnormalities may be associated with intracranial abnormalities.	Micropthalmia may be associated with coloboma, congenital infections, retinopathy of prematurity, or persistent hyperplastic primary vitreous (PHPV). May see hypertelorism or hyperplastic ethmoid air cells.
Postenucleation/radiotherapy	CT: orbital growth ceases. May get thickening of the orbital walls with time.	Get a greater degree of deformity in younger children.
Fibrous dysplasia	Radiograph/CT: sclerotic ground-glass appearance with thickening and resultant decreased orbital size.	When also involving adjacent facial bones, there is leonine appearance (leontiasis ossea).
Osteopetrosis/thalassemia/severe anaemia	Radiograph/CT: due to hyperostosis.
Mass effect from expansile process in adjacent sinus Fig. 4.114	CT/MRI: orbital walls are displaced causing deformity and decreased size.	Usually mucocoele or tumor.

Fig. 4.114 Mass effect from expansile process in adjacent sinus. T1-weighted postcontrast coronal MRI shows right frontal ossifying fibroma displacing orbital roof.

**Table 4.25 Enlarged orbit**
Diagnosis	Findings	Comments
Macrocephaly/hydrocephalus	All imaging modalities: spurious enlargement due to large skull.	Bilateral and symmetric.
Buphthalmos Fig. 4.115, p. 370	Radiograph/CT: asymmetrical enlargement with characteristic globe appearance. Need to exclude tumor.	(see Table 4.29 )
Orbital space-occupying lesion	All imaging modalities: degree of enlargement related to rate of growth of lesion.	Orbital enlargement not uncommon.
NF Fig. 4.116, p. 370	Radiograph/CT: elevation of lesser wing of sphenoid and associated dysplasia giving “bare orbit” appearance. Also, see widening of the optic canal.	Usually unilateral. Need MRI to assess for associated optic glioma.

Fig. 4.115 Axial noncontrast CT shows right buphthalmos with enlarged, elongated right globe.

Fig. 4.116 T2 axial MRI shows left buphthalmos, sphenoid wing dysplasia, and frontotemporal plexiform neurofibroma showing the characteristic “target” sign appearance (hyperintense periphery/hypointense center) in NF1.

**Table 4.26 Hypertelorism**
Diagnosis	Findings	Comments
Micro-/anophthalmia	Due to compensatory enlargement of ethmoid air cells.	(see Table 4.24 )
Craniosynostosis Fig. 4.117	In bicoronal synostosis and related syndromes (Apert, Crouzon, and Pfeiffer syndromes).
Greig syndrome	Dolichocephaly, anomalies of facial bones and extremeties.	Mental retardation.
Fibrous dysplasia	Involving ethmoid air cells with characteristic findings.	(see Table 4.31 )
Midline facial defects/cephalocoeles Fig. 4.118 Fig. 4.119	CT: thin-slice axial and coronal shows defect in frontal bone. MRI: assessment of cranial contents and associated brain abnormalities.

Interorbital distance is greater than normal.
Mild hypertelorism occurs in multiple syndromes (cleidocranial dysostosis/trisomy 13/Hurler syndrome/thalassemia).
It may be isolated, familial, and of no clinical significance.

Fig. 4.117 Coronal 3D CT shows bicoronal synostosis with harlequin eye appearance and hypertelorism.

Fig. 4.118 Coronal CT (bone window) shows nasoethmoidal cephalocele, a defect in the left frontal bone with herniation of intracranial contents into left ethmoid air cells and resultant hypertelorism.

Fig. 4.119 T2 axial MRI shows hypertelorism due to nasofrontal cephalocele.

**Table 4.27 Hypotelorism**
Diagnosis	Findings	Comments
Down syndrome	Small calvarium and hypoplastic maxillae.
Metopic and sagittal synostosis Fig. 4.120	Radiographs/CT: characteristic skull shape with premature fusion of metopic and sagittal sutures.	May see hypoplastic ethmoid sinuses.
Holoprosencephaly	CT/MRI: Midline malformation. Alobar is most severe.	Associated with midface hypoplasia.

Fig. 4.120 AP skull radiograph shows metopic synostosis with me-dial and upward angulation of the orbits and hypotelorism.

**Table 4.28 Microphthalmia**
Diagnosis	Findings	Comments
Congenital	CT/MRI: Small globe (see Table 4.24 ). MRI is best imaging modality to assess internal structure of globe, ocular contents, and brain.	Many chromosomal abnormalities: sporadic, AD, recessive, and X-linked forms. One-third of cases have associated cranial malformations. Consider genetic counseling.
Congenital infections (rubella, CMV, syphilis)	CT: Small globe that may contain calcification. Usually have other manifestations of disease; therefore, CT brain indicated to assess for calcification.	Uni- or bilateral.
Persistent hyperplastic primary vitreous	CT: High-density vitreous. No calcification.	Leukocoria at birth (see Table 4.30 ).
Retinopathy of prematurity	Leukocoria.	Appropriate clinical history (see Table 4.30 ).
Trauma Fig. 4.121	All imaging modalities: small, shrunken, distorted globe.	Appropriate history.
Phthisis bulbi	CT: small calcified globe.	End result of destructive process.
Maternal exposure (alcohol, benomyl, thalidomide, retinoic acid, lysergic acid diethylamide [also known as LSD], hydantoin)	Small globe that may contain normal anatomic structures or be malformed.	Correlate with clinical history.
Surgery	Imaging findings depend on cause of surgery.	Appropriate history.

Globe with total axial length < 2 standard deviations below mean for age
Less than 19 mm in 1 year old and < 21 mm in adult

Fig. 4.121 Posttrauma axial noncontrast CT shows distorted small left globe due to rupture.

**Table 4.29 Macrophthalmia/buphthalmos**
Diagnosis	Findings	Comments
Isolated buphthalmos Fig. 4.115, p. 370	Enlarged globe, proptosis, and eyelid swelling without raised pressure.
Congenital glaucoma	CT/MRI: enlarged, elongated globe with clinical finding of increased pressure—primary and bilateral in 80%.	Child < 3 y. Medical or surgical treatment indicated. If not treated, follow-up imaging will show progressive decrease in size of globe.
Axial myopia	Enlargement of AP diameter of the globe.	Present with visual impairment. Older children.
Colobomatous macrophthalmia	Syndrome of macrophthalmia, coloboma, and microcornea.	AD.
Phakomatoses (NF1 and Sturge-Weber syndrome) Fig. 4.116, p. 370	CT: Enlarged, elongated globe. Look for sphenoid wing dysplasia and plexiform neurofibroma in NF and characteristic intracranial appearances in SturgeWeber syndrome.	NF: it was thought that plexiform neurofibroma infiltrates angle of ciliary body. Occurs in 50%. Sturge-Weber syndrome: angiomatous change in ciliary body or angle of anterior chamber.
Intraocular mass	Enlarged globe with intraocular mass.	(see Table 4.33 )
Staphyloma	CT: focal bulge posteriorly with thinning of the sclera.	Infections, scleritis, trauma, and glaucoma predispose to development of focal bupthalmos.

Globe is larger than normal for age.
Greater than 12 mm in infants.
Greater than 23.5 mm in the mature globe.

**Table 4.30 Leukokoria**
Diagnosis	Findings	Comments
Retinoblastoma Fig. 4.122 Fig. 4.123	CT: Non-contrast–enhanced CT (NECT) best for identifying calcification. CECT sees variable enhancement of noncalcified portion of mass and normal sized/enlarged globe. MRI: Best for extraocular and intracranial disease. Mass hyperintense on T1 and hypointense on T2 relative to vitreous. Postcontrast heterogeneous enhancement. Image whole brain to assess for pineal (trilateral) and suprasellar (quadrilateral) disease.	Calcification rarely seen in other lesions in children < 3 y. Unilateral in 75%. Bilateral and multifocal in 25% is more often familial and must be screened for pineal and suprasellar involvement.
PHPV Fig. 4.124	NECT: Microphthalmia, small irregular lens, no calcification, and hyperdense vitreous chamber. Abnormal vitreal tissue may enhance. Linear hyperdensity extending from retina to lens represents Cloquet canal and persistent hyaloid artery. MRI: High-signal vitreous on T1 and T2, fluid levels as a result of hemorrhage. Also demonstrates canal as previously.	Presents in infancy with leukocoria, microphthalmia, and cataract. Sporadic disease unilateral; bilateral usually part of multisystem syndrome.
Coats disease Fig. 4.125	CT: High-density vitreous, no calcification, and is indistinguishable from noncalcified retinoblastoma. Vitreous contains wing-shaped retinal detachment. MRI: superior for subretinal effusion—high signal on T1 and T2.	Usually boys, unilateral. Present from birth but present near end of first decade when retina detaches and vision deteriorates.
Retinopathy of prematurity	CT: Noncalcified, retrolental, hyperdense mass that may be associated with retinal detachment. May be calcified and microphthalmic if chronic. MRI: findings nonspecific.	Uni- or bilateral in setting of appropriate medical history.
Toxocara canis infection	CT: opaque vitreous or a localized irregular, nonenhancing retinal mass. No calcification.	Present at approximate 6 y. History of close contact with dogs and positive serology are suggestive.
Retinal astrocytoma	CT/MRI: intraocular mass (es) with or without exudative retinal detachment, hemorrhage, and calcification.	Rare; isolated or in association with tuberous sclerosis or less commonly NF or retinitis pigmentosa. May be bilateral.
Retinal hemangioma	CT/MRI: Hemorrhage and often retinal detachment. Post-CE of retina.	Rare.
Medulloepithelioma	CT/MRI: markedly enhancing tumor that may erode the orbital wall or induce hyperostosis.	Rare tumor located anterior to the iris. Occasionally may arise next to the optic nerve. Lack of calcification helps differentiate it from retinoblastoma.
Retinal dysplasia/Norrie disease	CT: microphthalmia and dense vitreous with blood-fluid level. Often also have calcification and retinal detachment.	X-linked recessive, have seizures, mental deficiency and deafness by age 4 y.

Fig. 4.122 Coronal CT (bone window) shows bilateral calcified intraocular masses consistent with retinoblastomas.

Fig. 4.123 T2-weighted fat-saturated sagittal oblique MRI shows intraocular mass with extension into proximal optic nerve and showing T2-weighted hypointensity in keeping with calcification—traits that are characteristic of a retinoblastoma.

Fig. 4.124 Persistent hyperplastic primary vitreous. Axial noncontrasted CT shows high-density fluid level in PHPV due to hemorrhage within the right eye.

Fig. 4.125 Axial noncontrast CT shows high-density vitreous without focal mass or calcification in Coats disease of the right eye.

**Table 4.31 Orbital sclerosis**
Diagnosis	Findings	Comments
Fibrous dysplasia	Radiograph/CT: sclerosis, hyperostosis, and bone expansion of one or both orbits. Characteristic ground-glass appearance.	May also have exophthalmos.
LCH	Radiograph/CT: in the healing phase previously lucent lesion will show sclerosis.	Skeletal survey may show other characteristic bone lesions.
Chronic osteomyelitis	Radiograph/CT: sclerosis adjacent to chronically infected frontal sinus.
Osteoma	Radiograph/CT: Well circumscribed sclerotic lesion in frontal sinus. Orbital roof can be displaced and sclerotic.
Osteopetrosis	Radiograph/CT: sclerosing dysplasia with widespread bone involvement.	Skeletal survey will show characteristic appearance of long bones and spine.
Infantile cortical hyperostosis (Caffey disease)	Radiograph/CT: thickening and sclerosis of predominantly upper and lateral orbital walls.	Skeletal survey will show other areas of involvement especially mandible (see Table 4.45 ).
Radiotherapy	Radiograph/CT: sclerosis posttargeted radiotherapy.	Correlate with history.

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Tags: 4 Skull, and Vertebral Column, Differential Diagnosis in Pediatric Imaging, Intracranial Space, Pediatric & Neonatal Medicine, Radiology (incl. Interventional Radiology)

Jul 12, 2020 | Posted by drzezo in PEDIATRIC IMAGING | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access