CT and MRI Imaging Spectrum of Orbital Masses: A Pictorial Essay and Review of the Literature

Michael L. O’Neill, M.D., Gabriela De La Vega, M.D., Paul Cofnas, BS, Natalya Nagornaya, M.D., Rita Bhatia, M.D.

Jackson Memorial Hospital/University of Miami School of Medicine

Orbital masses can result from a wide spectrum of etiologies and can often be challenging to diagnose with certainty The imaging appearance of orbital masses can also be highly variable Possible etiologies of orbital masses can routinely include Malignant Neoplasms, Vascular Lesions, Benign Neoplasms, Congenital Lesions, Inflammatory/Infectious Lesions and Miscellanous etiologies( Including Thyroid eye disease, Anatomic EOM variants, Optic Nerve Drusen, Fibrous Dysplasia, Tolosa-Hunt Syndrome, MelanocyticHamartoma, Orbital Mucocele, Amyloid, and Sub-periosteal Orbital Hematoma).

Introduction

Conclusions

Methods A retrospective review of orbital mass cases in children and adults was performed, spanning a time range of approximately 10 years. The respective etiologies of the lesions were ascertained and catalogued The associated CT and MRI imaging findings were reviewed and compared with those previously described in the literature in each instance.

MRI and a CECT images obtained on a 46 y/o female patient with history of Grave’s eye disease and multiple orbital decompressive surgeries and radiation therapy show diffuse enlargement of all the right EOM and compression of the optic nerve. There is increased T2 signal and homogeneous enhancement on post contrast images.

Thyroid Orbitopathy Lymphocyte-mediated inflammatory process that affects EOMs Most common cause of exophthalmos in adults 30-50% of Grave’s patients have significant orbital disease, bilateral in 90% and symmetrical in 70% of cases CT: isodense enlargement of EOMs, prominent intraconal fat, enhancement of EOM increases MRI: isointense enlargement of EOM in T1WI, with increased enhancement on post contrast images, EOMs are hyperintense on T2WI

Autoimmune Thyroid Orbitopathy

References 1. Albert, D. (2000). Principles and Practice of Opthamology. 2nd Edition. Philadelphia: WB Saunders. 2. Burton P. Drayer, M. (2005). Neuroimaging Clinics of North America. Philadelphia, PA.: Saunders, Inc. 3. Weiss, S. E. (2001). Enzinger and Weiss's Soft Tissue Tumors. 4th Edition. St. Louis: CV Mosby. 4. Wendy, R. E. (2008). Vascular Orbital Lesions of the Orbit: More Than Meets the Eye. Radiographics , 185-205

Multiple MRI images including dynamic phase obtained in a 76 y/o female patient with history of Multiple Myeloma and left orbital mass demonstrate a circumscribed left retro-orbital intraconal mass lesion with hyperintense T2 signal, that showed early patchy central enhancement and showed progressive accumulation of contrast in the late phases.

Cavernous Malformation Most common vascular lesions in adults, most often seen in women between the ages of 18-72 years Slowly and progressively enlarge and do not involute, therefore, usually present as progressive, painless proptosis CT: well-circumscribed, early patchy central enhancement, microcalcifications may be seen, may displace adjacent structures but does not invade MRI: isointense to muscle on T1WI and hyperintense on T2WI, show progressive accumulation of contrast on late phase dynamic imaging

Vascular Cavernous Malformation

Post -Contrast CT and MR images of a 70 y/o male with significant proptosis of the left side and no light perception vision on left eye demonstrate a lobulated, poorly circumscribed mass with high T2 signal and heterogeneous enhancement. Final pathology confirmed the diagnosis.

Venolymphatic Malformation May be evident at birth but typically manifest in infancy or childhood May enlarge slowly with progressive proptosis or may present as abrupt hemorrhage after minor trauma or infection CT: multicystic hypodense mass with remodeling of bony orbit, variable enhancement MRI: fluid-fluid levels resulting from hemorrhages of various ages within multiple cysts are pathognomonic, lobulated, poorly circumscribed with variable signal on T1WI, T2WI has hyperintense signal, no flow voids, variable enhancement

Venolymphatic Malformation

Arteriovenous Malformation

Multiple MRI as well as DSA images in the frontal and lateral projections were obtained on a 32 y/o female patient who presented with exophthalmos and progressive vision loss. MRI images demonstrate a heterogenously enhancing vascular mass with multiple tortuous vessels and associated flow voids. DSA images confirm the diagnosis in demonstrating a large vascular nidus and an early draining vein.

Arteriovenous Malformation Multiple congenital microvascular connections between arteries and veins without an intervening capillary network Usually manifest with periorbital swelling, dilated retinal veins, visible or palpable pulsations, an audible bruit, and glaucoma CT and MR imaging with standard and angiographic protocols can help in the diagnosis Conventional angiography is typically required for precise definition and treatment planning

Hemangiopericytoma

Contrast enhanced CT and MR images of a 83 y/o female patient with proptosis show a well-circumscribed, elongated and lobulated intraconal mass that appears to originate from the lateral and anterior aspect of the orbit with intermediate signal on T2WI with few vascular flow voids and avid enhancement both on T1 FS GAD and CT images.

Hemangiopericytoma Rare, may occur at any age Usually present as slowly progressive, painful proptosis and decreased visual acuity Typical location is extraconal, in the adjacent paranasal sinuses CT: homogeneous, lobulated, encapsulated, well-circumscribed, intense enhancement, especially in early arterial and venous phase with rapid washout MRI: signal similar to grey-matter on T1WI and hyperintense on T2WI

MR images obtained on a 2 y/omale who presented with a 1 yr. history of "lazy right eye“ and right eyelid swellings how a lobulated lesion arising in the superior right orbit inseparable from the superior rectus muscle with low signal on T1 and high signal on T2 and heterogeneous enhancement on post contrast images. PET/CT image shows an FDG-avid right extraconal mass.

Orbital Rhabdomyosarcoma Most common mesenchymal tumor in children and most common extraocular orbital tumor in children that usually manifests in the first decade of life Aggressive, rapidly growing and usually manifests with rapidly progressive proptosis, conjunctival and palpebral swelling which may simulate orbital cellulitis CT: extraconal, irregular, ovoid, well-circumscribed, homogeneous mass that is isoattenuated relative to muscle, calcification may be seen, may erode bone MRI: isointense to muscle on T1WI and hyperintense on T2WI, intraorbital structures may been cased, moderate to high enhanement, globe may be displaced but rarely invaded, but may invade adjacent sinuses

Coronal and axial CT images obtained from a 90y/o female patient with history of breast cancer who presented with proptosis show a heterogenous enhancing left intraconal orbital mass and enopthalmos of the left globe. Mass is inseparable from the EOM and optic nerve. Final Pathology showed metastatic Scirrous Breast Carcinoma.

Metastatic Disease Orbit is occasionally the site of metastatic deposits commonly from breast or lung carcinoma and neuroblastoma in children Any structure in the orbit may be affected but it typically affects the posterior aspect of the globe because they reach the eye via the posterior cilliary arteries and they may affect EOM, bone destruction is common Both eyes are affected in one third of cases CT and MRI findings are variable depending on the primary tumor and the location Typically a poorly marginated mass is seen in the extraconal space with bony invasion and moderate contrast enhancement MR is superior to CT for distinguishing from melanomas but the findings are nonspecific with usually low TI and high T2 signal

Multiple MR images obtained on a 69 y.o. male with several month history of worsening bilateral proptosis show a diffuse infiltrative process bilaterally involving the retrobulbar soft tissues predominantly isointense to grey matter on T1WI and slightly hyperintense to T2 (not shown) with significant enhancement on post contrast images. Tumor encases the optic nerves, involves the lacrimal glands and extends into the infraorbital foramina. The temporalis muscles are enlarged and also show abnormal enhancement.

Lymphoproliferative Lesions of the Orbit Affects patients after the 6th decade and presents as either an indolent painless mass, a fulminant mass, a regional bony mass, or with neuro-ophthalmic manifestations (CNS disease) Imaging shows a homogeneous enhancing solid tumor anywhere in the orbit, bilateral in 25%, but may present with primary EOM involvement simulating thyroid orbitopathy and a diffuse infiltrative form may occur CT: iso to hyperdense, homogeneous with moderate diffuse enhancement MRI: mildly hyperintense to muscle on T1WI and T2WI, moderate to marked homogeneous enhancement, may show diffusion restriction

MR images on a 41 y/o male with no known medical history show a rounded intraocular mass that is high in T1 and low on T2 with homogeneous enhancement with no evidence of extension beyond the sclera in keeping with the signal characteristics of malignant melanoma.

Ocular Melanoma Most common primary intraocular tumor in adults Peak incidence in 6th decade, slight male preference 50-70% 10-year survival May metastasize to liver, lung, bone and kidney May present with painless visual disturbance and photopsia, but are frequently asymptomatic and found incidentally CT: Solid soft tissue density mass with diffuse enhancement MRI: hyperintense on T1WI, hypointense on T2WI, diffuse tumor enhancement on post contrast images

Multiple MRI images obtained on a 3 month-old male patient with a 2 week history of proptosis, demonstrate aggressive bilateral lobulated, mildly heterogenous enhancing masses involving the optic nerves and extending posteriorly to the optic chiasm.

Optic Nerve Glioma Subtypes: childhood benign +/- NF1 or adult malignant Most common presentation is decreased vision, proptosis, nystagmus, opticatrophy In children with NF1 it usually affects the anterior pathway and 50% extends posteriorly to involve the optic pathway In children without NF1 it mainly affects the chiasm and retrochiasmal Imaging usually shows a sausage-shaped enlargement of the optic nerve and chiasm with kinking or buckling of the nerve Enhancement may range from none to intense homogeneous CT: isodense, no calcifications, enlargement of bony optic canal MRI: iso to hypointense onT1WI, hyperintense on T2WI

Malignant Tumors

Optic Glioma

Orbital Lymphoma

Ocular Melanoma

Metastatic Disease

Orbital Rhabdomyosarcoma

Benign Tumors Nerve Sheath Tumor-Neurofibroma

Post-Contrast CT and MR images obtained on a 43 y/o female patient who presented with left-sided proptosis show a circumscribed, peripherally enhancing lesion that has low T1 and high T2 signal intensity with low signal at periphery giving it a “target” appearance, involving the superolateral aspect of the left orbit with associated mass effect on the globe, as well as the medial and lateral rectus muscles.

Neurofibroma Ophthalmic divion of CNV is the most likely source; optic nerve is not affected because it is covered by meninges Plexiform neurofribromas occur in children with NF1 and are usually diffusely infiltrating, nonencapsulated and highly vascular Solitary neurofibromas are usually spherical or ovoid, well-circumscribed masses that typically occur in the superior orbit and or lacrimal gland fossa and are more common in the third to fifth decade of life CT: isodense to muscle with uniform contrast enhancement MRI: iso or hypointense to muscle on T1WI, and hyperintenseon T2WI and may show a “target” appearance (hypointense at periphery) MR is superior to CT for distinguishing from melanomas but the findings are nonspecific with usually low TI and high T2 signal

Nerve Sheath Tumor-Schwannoma

Optic Nerve Sheath Meningioma

Coronal T2 and T1 and axial T1 FS GAD of a 38-year-old woman who presents with worsening proptosis, diplopia, and vision loss demonstrate a well-circumscribed , oval-shaped, heterogeneous avidly enhancing soft-tissue mass in the superior extraconal region of the left orbit with consequent inferomedial displacement of the superior rectus muscle and the optic nerve.

Schwannoma Usually benign isolated lesions that occur in adults, unless associated to NF2 Maybe associated to loss of function of theassociated nerve, maybe asymptomatic or present as slow progressive proptosis and diplopia CT: isoattenuating relative to brain parenchyma, calcifications and hemorrhage are rare, homogeneous enhancement, may produce remodeling of adjacent bone MRI: homogeneous, hypotoisointense to grey matter on T1WI and hypointenseto CSF on T2WI, may show cystic degeneration and therefore heterogeneous signal, usually demonstrate homogeneous enhancement Maybe difficult to differentiate from neurofibromas unless they are partially cystic or contain intramural hemorrhage which helps to distinguish them

Coronal T1 FS GAD, coronal T2 and sagital CT images of a 41 yo female who presented with inability to reach full upward gaze and diplopia demonstrate an intraconal mass within the posterior third of the orbit that extends into the orbital apex and encases the left optic nerve with scalloping and expansion of the surrounding bony orbital walls.

Optic Nerve Sheath Meningioma Patients usually present with painless, progressive, unilateral vision loss and proptosis Typically presents in the 4th-5th decade In young patients it is usually more aggressive and more likely to be related to NF2 CT: solid, tubular, well-defined enlargement of optic nerve complex, linear or punctate calcifications, hyperostosis, homogeneous enhancement MRI: isointense on T1WI, hyper to hypointense on T2WI, perioptic cysts are seen

Congenital Orbital Dermoid

Coronal T1WI, T1WI FS, and T2WI obtained in a 20 y/o female patient with a right upper lid lesion show a well-circumscribed mass with homogeneous signal intensity characterized by hyperintense T1 signal with suppression of signal on fat suppression, low signal on T2 and no evidence of enhancement. Final Pathology confirmed the diagnosis of Dermoid.

CT images of a 68 y/o female patient who presented with decreased visual acuity, swelling, and dryness of left eye demonstrate a large heterogeneous intraconal mass with peripheral enhancement. There is proptosis and adjacent bony remodeling of the medial and posterolateral wall of the orbit.

Teratoma

Mass lesion of orbit that results from congenital epithelial inclusion. If it contains epithelial and dermal appendages it is called a Dermoid. An epidermoid has only epithelial elements. Mean age of diagnosis is late teens to early 20s and it usually presents as a nontender, firm, subcutaneous mass near the orbital rim. CT: May present with hypodense fat and/or calcifications with evidence of osseous remodeling with smooth, scalloped margins and rim-enhancement MRI: hyperintense on T1WI and suppression of lipid signal on fat suppression sequences , iso or hypointense on T2WI with heterogeneous debris, rim-enhancement on post contrast images

Itra cranial teratomas are usually congenital, detected in utero or in neonatal period and affect males more than females Contain elements from all three germinal layers and may be mature (fully differentiated) or immature or malignant (resembles fetal tissue) CT: heterogeneous mass that may have fat and soft tissue density, calcifications and cystic components, with enhancement of the soft tissue components and may cause bony erosion MRI: hyperintense on T1WI due to fat, soft tissue components will be iso- to hyperintense on T2WI and will enhance

Inflammatory Orbital Sarcoidosis

76 y/o female patient who presented with right eye proptosis and decreased vision. Axial CT demonstrates diffuse enlargement of the extraocular muscles with relative sparing of the tendinous insertions. Dense calcification was noted in the markedly enlarged left medial rectus muscle. The soft tissue around the right optic nerve results in a “pseudomeningiomatous “ appearance. Axial T2 WI shows the affected muscles to be hypointense. Axial T1WI demonstrates isointense signal intensity of the enlarged extraocular muscles with enhancement

Orbital Amyloidosis Systemic or focal disease with accumulation of amyloid Orbital disease in 4% of local disease Imaging will show a homogeneous mass with calcifications in extraconal orbit usually involving lacrimal fossa and gland Remodeling, erosion, hyperostosis, orsclerosis of adjacent bone may be seen Enlargement of EOMs with coarse or punctate calcifications may be present

Orbital Amyloidosis

MRI images obtained on a 20 y/o female who presented with pain around left eye and left temple and occasional numbness in left cheek and upper eyelid. There is a predominately extraconal low T1enhancing mass lesion involving the inferolateral aspect of the left orbit causing mass effect on the inferior and lateral rectus muscles. Final pathology confirmed the diagnosis of Orbital Sarcoidosis.

Orbital Sarcoidosis Non case ating granulomatous inflammation of orbit Broad presentation with systemic signs and symptoms but usually presents as acute uveitis or lacrimal gland enlargement in the 3rd-5th decades with a female predominance CT: optic nerve thickening with abnormal enhancement, isodense enlargement or masses MRI: isointense enlargement or masses on T1WI, hypo to hyperintense on T2WI, optic nerve and intraorbital mass enhancement

Lacrimal Gland Tumors Lacrimal Gland Adenoid Cystic Carcinoma

Multiple MR images of a 40 y/o female patient demonstrates a mass in the left lacrimal gland mass with a central area of hypointensity causing mass effect on the intraconal structures and enlargement of the left lateral rectus muscle.

Lacrimal Gland Adenoid Cystic Carcinoma Cell types of the lacrimal gland carcinomas include adenoid cystic, malignant mixed, mucoepidermoid, adenocacioma, squamous cell, and anaplastic May present as a painfull palpable mass in the lacrimal gland Propensity for perineural spread Imaging usually shows irregular margins and early bony invasion as well as early spread to the paranasal sinuses, cavernous sinuses and intracranial space MRI: tend to be hypointense on T1WI and isointense on T2WI but it may be variable It is not possible to differentiate the different cell types of carcinomas based on imaging alone

Pleomorphic Adenoma

Multiple MR images of a 24 y/o male with blurry vision, proptosis, and extraocular mass demonstrate an avidly enhancing oval shaped extra-conal soft tissue mass with slightly lobulated borders in the superior lateral aspect of the right orbit causing mass effect on the orbital content. The mass demonstrates heterogeneous intermediate T2 signal with multiple small cystic foci. CT scan reveals non aggressive pattern of bone remodeling with scalloping of the right orbital roof.

Pleomorphic Adenoma Halfof lacrimal gland masses are epithelial, the other half are lymphoid or inflamamtory, and of these half are benign mixed tumors (pleomorphic adenomas) and the rest are carcinomas Usually present with a painless palpable mass in the lacrimal gland fossa or proptosis On imaging they are usually well-marginated, heterogeneous lesions causing lacrimal gland enlargement with scalloping of the adjacent bone but no invasion and some degree of contrast enhancement

Lymphoma Lacrimal Sac Multiple MR images of an 83 y/o male patient show poorly marinated, homogeneously enhancing bilateral orbital masses predominantly infiltrating the extraconal space in the medial orbits with extension into the adjacent ethmoid sinuses, soft tissues over the nasal bridge, and extending into the bilateral nasolacrimal ducts.

Spectrum ranges from lymphoid hyperplasia to malignant lymphoma Tend to cause enlargement of the gland with homogeneous contrast enhancement Bone destruction seldom occurs, usually the tumor molds to the surrounding structures MRI: hypointense on T1WI and hypo to hyperintense on T2WI

Results

Pseudotumor

Langerhan Cell Histiocytosis

MR images show an evidly enhancing mass arising from the lateral wall of the right orbit with hypointense T1 signal and iso to hypointense signal on T2WI extending into the adjacent temporal soft tissues with mass effect on the orbital structures

Langerhan Cell Histiocytosis Reticulo endothelial disorder of unknown cause that may involve the orbits in 10-30% of cases Affects patients 5-20 years of age and has a male to female ratio of 2:1 Imaging usually shows extensive lytic bone destruction of the lateral orbital wall and the middle cranial fossa with an associated soft tissue mass in the orbit, typically in the lateral exrtaconal compartment CT: iso to hyperintense to muscle with prominent contrast enhancement MRI: hypo to isointense on T1WI and hypo to hyperintense on T2WI

MR images of a 42 y/o male patient with progressive hearing loss demonstrate enhancing soft tissue involving the right orbit predominantly extending in to the apex and involving the EOMs with amorphous enhancement of the retro-orbital fat

Pseudotumor/Idiopathic Orbital Inflammatory Disease Polymorphous infiltration of inflammatory cells with fibrosis, believed to be an immune-mediated process Most common painful orbital mass in adults which usually presents as acute onset of orbital pain, edema and inflammation CT: infiltrative or mass-like soft tissue involving any area of orbit (myositic is the most common pattern), with diffuse enhancement MRI: hypointese to normal muscle on T1WI, iso or hyperintense to muscle on T2WI, diffuse and irregular enhancement

The possible etiologies of orbital masses are numerous, and arriving at the correct imaging and clinical diagnosis can be challenging as a result. A working familiarity of the expected imaging appearance of common orbital masses can greatly inform the appropriate subsequent management of the patient and help prevent unnecessary procedures. The imaging findings were largely similar compared to those previously reported for most of the lesions although with the expected range of imaging findings commonly seen in particular entities

11 month-old hispanic male who presented with swelling on his right lower eyelid of 2 weeks of evolution unresponsive to antibiotics.