The Orbits: Orbital Masses
Fig. 4.122, p. 374
Fig. 4.123, p. 374
Radiograph/CT: usually calcified mass in child < 3 y.
(see Table 4.30 )
CT/MRI: usually intra-/extraconal but may spread to involve globe. Best imaged with MRI to assess extent.
(see Table 4.35 )
MRI: T1 hypointense mass related to choroids, which enhances with contrast. CT: enhancing mass.
Older children/teenagers. Best imaged with MRI.
Optic nerve glioma
MRI: Best to evaluate extent. Mass isointense/slightly hyperintense to normal white matter on T1 and T2 and shows prominent CE. Causes fusiform enlargement of nerve, which is buckled and kinked.
One-third in the setting of NF1 and characteristically bilateral.
CT/MRI: usually extraconal but some lesions intraconal.
(see Table 4.35 )
CT/MRI: unilateral or bilateral uveoscleral thickening with enhancement, an enhancing retro-ocular mass, or enlargement of extraocular muscles, tendons, and lacrimal gland.
Idiopathic disorder with inflammatory, lymphoid infiltration of intraorbital tissues.
Lymphoma and metastases
CT/MRI: Lymphoma: diffuse infiltration of entire intraconal region. Shows slight to moderate enhancement.
Lymphoma best imaged with MRI.
Metastases: neuroblastoma/rhabdomyosarcoma, usually also with extraconal and orbital wall involvement.
CT: Hyperdense if acute. CT best for evaluating fractures.
If traumatic, assess for foreign body.
CT/MRI: May be primary or secondary. Usually intraconal or involving muscle but may extend extraconal and intracranial. MRI best for extent: T1 iso-/hypoin-tense relative to muscle and T2 hyperintense. Degree of enhancement varies. Enhanced scans in coronal plane best for evaluating intracranial extension.
Usually embryonal subtype.
Fig. 4.129, p. 378
CT/MRI: well-demarcated, anterior extraconal mass with fatty, fluid, or mixed contents. Majority superolateral related to frontozygomatic suture. CT shows osseous remodelling ± fine calcification in cyst wall.
MRI if features are not diagnostic or suspect deep extension into sinuses, masticator space, or intracranially.
Fig. 4.130, p. 378
MRI: best for assessing extent.
CT: best for showing calcification.
Usually complex with cystic and solid elements, composed fat/fluid/calcium and soft tissue. Often marked expansion of the orbit and displacement of the globe.
Benign but cause severe progressive proptosis in infancy. Transspatial.
MRI is imaging modality of choice to show extent especially if suspected intracranial extension. Use enhanced T1 and T2, axial, and coronal planes. T1 iso- or hypointense, showing diffuse intense enhancement postcontrast. T2 heterogeneous/hyperintense with frequent flow voids. MRA unhelpful as vascular component is at capillary level.
CT: slightly hyperdense homogeneous mass with intense enhancement.
Usually present before 6 mo. Only imaged if symptomatic or fail to involute.
Lymphatic, venous, and venolymphatic malformations
MRI best to show extent; use fat-saturated axial and coronal sequences. See multilocular, transspatial, variably enhancing mass. Fluid-fluid levels with signal corresponding to age of blood products. Pure lymphatic malformation is nonenhancing. Venolymphatic variable.
Present in childhood with progressive, slow-growing mass. Usually extraconal but often transspatial.
Include brain imaging for associated intracranial abnormalities especially in venolymphatic malformations.
Malignancy (lacrimal gland/lymphoma/leukemia)
Fig. 4.131, p. 378
Primary lacrimal gland malignancy rare and associated with bony destruction.
Lymphoma/leukemia: well-defined high-density mass involving lacrimal gland or isolated soft-tissue mass.
May present with exophthalmos (see Table 4.36 ).
Orbital cellulitis/subperiosteal abscess
Fig. 4.132, p. 378
CECT: thickening and edema of orbital soft tissues representing cellulitis and/or phlegmon. Low-density, rim-enhancing area represents subperiosteal abscess. Usually extraconal but can extend intraconally. Procure axial and coronal images.
Need brain imaging (CT or MRI) to evaluate intracranial complications of sinusitis. MRI more sensitive.
Radiograph/CT: show defect or destruction often not confined to orbits. CT/MRI shows adjacent soft-tissue mass and exophthalmos.
Most common causes are neuroblastoma, hematological malignancy, rhabdomyosarcoma, and Ewing sarcoma.
Extension from lacrimal gland/tumor
Radiograph/CT/MRI: Localized wall expansion adjacent to tumor. Lesions have a sclerotic rim.
Spread of adjacent infection
CT: usually subperiosteal abscess but if longstanding may cause destruction of orbital wall.
Wall involvement usually due to aggressive pathogen particularly aggressive fungal sinus infections such as mucormycosis and aspergillosis (see Table 4.35 ).
CT: ethmoid or maxillary antral tumors invade by direct extension.
Radiograph/CT: Bony expansion of adjacent sinus, which protrudes into orbit. Sinus may be sclerotic if chronically infected. Contains nonenhancing soft tissue.
Present with unilateral proptosis. Most common is frontal sinus with palpable mass in superome-dial orbit.
Radiograph/CT: Single or multiple lytic lesions with beveled edges and adjacent soft-tissue mass. Often have exophthalmos.
MRI needed if sphenoid bone involved and present with diabetes insipidus.
Need skeletal survey to look for other bone lesions.
You may also need
- The Neck
- The Orbits
- The Pediatric Vertebral Column: Anomalies of the Intervertebral Foramina
- Nasal Cavity: The Nares and Nasal Passages
- The Temporal Bone: Syndromes Associated With Ear Anomalies
- The Pediatric Vertebral Column: The Spinal Canal and Its Contents
- Oral Cavity: The Pharynx
- Sutures and Fontanelles