Orbital masses

From EyeWiki


Disease Entity

Disease

Masses that appear in the orbit can have a wide variety of etiologies, requiring careful examination and history-taking. Causes may include anything from benign lesions to malignant, life-threatening neoplasms that require urgent management. This article is meant to provide a brief overview of some common and uncommon causes of orbital masses, preferred methods of diagnosis, and treatment of these conditions.

Further detail about these processes can be found in their respective EyeWiki articles with hyperlinks provided for those available.

Infection

A wide variety of infectious etiologies exist that may cause masses in the orbit. When faced with an orbital inflammatory process, infections should remain at the top of the list of differential diagnoses[1]. The most common bacterial infections of the orbit are Staphylococcus aureus, Streptococcus, and HiB[1]. Mycobacterium tuberculosis and Pseudomonas aeruginosa may also be more uncommon causes of orbital masses secondary to infection[1] Most commonly, orbital involvement is secondary to paranasal sinus infection or direct pathogen exposure to the orbit from traumatic causes. Fungal etiologies may be more difficult to initially diagnose, causing increased risk of paranasal sinus invasion especially in immunocompromised patients. This sinus disease further increases the risk of secondary orbital infection. Rhizopus oryzae and Aspergillus are two specific fungal etiologies of concern for ophthalmologists. Parasitic infections can also occur secondary to pathogens such as Cysticercus, Taenia solium, and Echinococcus although these conditions are more common in developing countries. Specifics of these disorders may be found in their respective articles.[1]

Inflammatory

IgG4-Related Sclerosing Disease

An inflammatory disorder characterized by both increased serum levels of IgG4 and the presence of IgG4-positive plasma cells in affected tissues, IgG4-related sclerosing disease can present with a mass-like lesion in affected organs, including the orbit[1]. However, the most classic association described since the first report of the disease in 2001 has been autoimmune pancreatitis[2]. Within the orbit, the most common location tends to be the lacrimal gland[3][1]. Presentation can be unilateral or bilateral, with features ranging from painless proptosis, decreased visual acuity, tearing, redness, or photopsias depending on the involved areas of the orbit[3][2]. Extraocular involvement is associated with bilateral cases and cases involving the lacrimal gland[2].Diagnosis of IgG4-related sclerosing disease revolves around recognition of clinical features combined with biopsy and histopathologic examination of tissue showing lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis (although obliterative phlebitis is less common in the ocular form of IgG4 disease)[3][2]. Guidelines released in 2012 require these typical morphological features on biopsy as a basis for diagnosis[2][3]. Imaging can be performed, and should show enlargement or a mass in at least one organ, but is not required for diagnosis[3].

Treatment of this disease is difficult due to the lack of solid prospective, randomized clinical trials However, corticosteroids, rituximab, and radiation therapy have been attempted with varying results in case reports[3]. For more information see: IgG4-related Orbital Inflammation

Nonspecific (Idiopathic) Orbital Inflammation

Also known as orbital inflammatory pseudotumor, this idiopathic process presents with tumor-like symptoms with a pleomorphic cellular response and fibrovascular tissue reactions[4]. Typical presentation revolves around acute onset, rapidly progressive deep, boring orbital pain and headache. Proptosis, lid swelling, chemosis, and decreased ocular motility with tenderness may be present as well. Vision loss can occur, but is less common than double vision, pain with eye movement, or light sensitivity. Classically symptoms are unilateral, but children typically present with bilateral disease. Subclassifications exist based on the location of the disease and can be categorized as anterior, diffuse or posterior and pathological findings after biopsy and histopathologic evaluation, which can vary widely.Diagnosis is made by excluding conditions such as granulomatosis with polyangiitis, GCA, SLE, dermatomyositis, and rheumatoid arthritis. Biopsy may be used to aid in diagnoses that are unclear or the etiology remains in question after medical therapy is ineffective or incomplete.Treatment revolves around administration of corticosteroids, radiotherapy, and other immunosuppressants like methotrexate, cyclosporine, and infliximab[4]

For more information see: nonspecific orbital inflammation.

Vascular Lesions

Capillary (Infantile) Hemangioma

These are the most common tumors of infancy. Typically appear as a reddish macule within the first 6 months of life, this proliferates for up to 10 months before involuting, which may take up to 10 years to complete[5]. Diagnosis is usually clinical without any imaging studies needed, but contrast-enhanced MRI is preferred if imaging is necessary.[5]

For more information see: capillary hemangioma.

Cavernous Hemangioma

A solitary, encapsulated venous-lymphatic malformation that is the most common vascular mass found in the orbit.[6] Usually presents as painless proptosis in middle-aged women. However, it can also present with pain, lid swelling, diplopia, lump, and recurrent obstructed vision. These masses are typically unilateral and solitary with a low risk of bleeding due to support of the surrounding fibrous tissue[5]. For more information see: https://eyewiki.org/Cavernous_hemangioma

Lymphangioma

A benign malformation of the venous lymphatic system, lymphagiomas commonly affect children and rarely involved the orbit.[5] Symptoms occur quickly secondary to intralesional hemorrhage and include swelling, intraorbital hemorrhage, ocular proptosis, blepharoproptosis, and cellulitis[5]. Swelling has also been noticed after upper respiratory infection in some patients[7]. It can be differentiated from cavernous hemangioma by its distinct infiltrative, trans-spatial growth pattern[5]. CT may be used to aid in diagnosis and may show phleboliths in the venous compartment of the lesions and bony abnormalities. MRI is more useful to locate the lesions in the orbit and identifying its vascular composition. Management of this condition revolves around either sclerotherapy or resection, with many patients requiring multiple interventions[7].

Orbital Venous Varices

Orbital venous varices (AKA orbital varices), are venous malformations that consist of low-pressure plexuses that may “intermingle” with other proper orbital vessels[8]. Orbital varices may rarely present with periorbital pain, intermittent proptosis, vision loss, or an orbital mass. They are rare, abnormally thin-walled veins that are typically distensible[9]. Since they are part of the venous system, the flow is typically low, causing them to be classically asymptomatic.[9] They can cause intermittent proptosis which can be induced by increasing the orbital pressure by Valsalva, coughing, or straining. [8]Cases have been reported of thrombosis of these varices, causing intermittent periorbital pain, unilateral proptosis, or acute visual loss. Diagnosis is made with contrast-enhanced CT of the head and orbits showing a non-heterogeneous, serpiginous soft tissue mass in the orbit[9]. Treatment may include conservative management with LMWH if a thrombus is present, however surgical excision or endovascular CO2 laser ablation have been attempted with success for more serious cases[9].

For more information see: orbital varices.

Arteriovenous Malformation

Arteriovenous malformations (AVMs) are high-flow, communications between arteries and veins that bypass normal capillary beds, with multiple feeder arteries, a central nidus, and numerous dilated draining veins[10]. Most cases are thought to be of a congenital origin, and may enlarge over time[11]. They are different from other orbital tumors, in that they have a propensity to enlarge, bleed , ulcerate and in very rare circumstances, cause heart failure. AVMs may appear in the orbit, possibly causing proptosis, eyelid distortion, diplopia, and vision loss[12]. Diagnosis can be made clinically and confirmed with imaging, with MRI and confirmed by angiography. The diagnosis can be made histologically, but this is typically not recommended due to a rather high risk of bleeding.[12][11] Histologic examination shows thick-walled, irregular arterial and venous channels with and without stromal hemorrhage. Various treatment options have been reported, with some AVMs, with most instances requiring embolization procedures with resection[11]. Radical or partial resection of AVMs have also been reported with success in some patients.[11][12]

Cavernous Sinus Thrombosis

Cavernous sinus thrombosis (CST) is a rare, life-threatening disease. Rapid identification and treatment of this diagnosis is critical in decreasing long-term morbidity and mortality in patients who present with this condition. CST can be caused by infectious or aseptic etiologies, with aseptic cases usually occurring after surgery or trauma. Infectious causes can be spread from sinusitis, otitis, odontogenic sources, or orbital cellulitis; most often by spread of infection to veins or by direct extension of the infection. The most commonly isolated organism is Staphylococcus aureus (around 70% of cases). Patients will often present with signs of sepsis and headache in a unilateral, frontotemporal or retrobulbar distribution. Ocular symptoms may be secondary to venous congestion, with up to 90% of cases showing chemosis, periorbital edema, ophthalmoplegia, vision loss, and proptosis. These symptoms tend to start unilaterally before spreading to the contralateral eye within 48 hours. Imaging can be performed with CT or MRI, however clinical presentation and history alone may be enough to confirm the diagnosis. Treatment involves both surgery and intravenous antibiotics, with steroids and anticoagulation currently having conflicting evidence in the literature[13].

Carotid-Cavernous Fistula

Carotid-cavernous fistulas (CCFs) are abnormal communications between the arterial and venous circulation within the cavernous sinus. These are thought to involve primary thrombosis of the venous outflow of the cavernous sinus, with changes in the surrounding vasculature to provide proper collateral flow[14]. The most common cause of CCF formation is trauma, which accounts for up to 75% of cases[15]. Presenting symptoms depend on the location of the CCF in the cavernous sinus, with posteriorly draining fistulas causing more neurologic symptoms, and anteriorly draining fistulas causing more ocular symptoms. These ocular symptoms may include diplopia, tearing, red eye, blurred vision, headache, and proptosis. Clinical signs may include proptosis that may possibly be pulsating, a red eye, chemosis, orbital congestion, an ocular bruit, and possibly CRVO in cases of significantly raised episcleral venous pressure. The presence of many of these clinical signs depend on the level of flow within the CCF[14]. Diagnosis often involves ultrasound, CT imaging, MRI with MRA, with digital subtraction angiography remaining the gold standard for classification and diagnosis[15]. [14]Current first-line treatment involves endovascular embolization, however when an endovascular approach is not possible stereotactic radiosurgery can be considered[14].

Benign Tumors

Optic Nerve Sheath Meningioma

Typically presents as painless, progressive vision loss and proptosis in a middle-aged women (age 30-50)[5]. Although lesions are typically unilateral, bilateral conditions have been reported and may occur in conditions like type II neurofibromatosis[16][17][5]. Optic nerve sheath meningiomas may be classified as either primary or secondary; with primary arising from capillary cells of the arachnoid and secondary arising from the sphenoid ridge, tuberculum sellae, or olfactory groove before invading the optic canal and orbit[5]. Invasion of the orbit may produce visual disturbance initially before progressing to optic neuropathy, proptosis, and strabismus at later stages. [5]

The preferred method of imaging is a CT scan that will show a homogenously enhancing mass that surrounds the optic nerve, and may present with a “tram-track” sign or “target”-like enhancement. The adjacent bone may show hypersostosis in meningiomas.[5]

For more information see: optic nerve sheath meningioma.

Schwannoma

Schwannomas are nerve sheath tumor that constitutes around 1% of orbital tumors. The orbital tumors tend to appear in young and middle-aged adults, arising from the intraorbital branches of cranial nerve V1. [5]Symptoms that arise tend to be secondary to mass effect and include gradual nonpulsating proptosis and lid swelling early, and diplopia, ocular motility restriction, mild visual acuity impairment, and symptoms of optic nerve compression later in the diseases progression[18]. Proptosis tends to occur inferiorly, as the primary involvement in 40-60% of orbital schwannomas is located in the superior quadrant[18]. Because of this superior quadrant involvement, anywhere from 16-24% of orbital schwannomas can extend into the superior orbital fissure[19][18].

CT imaging shows iso- or hypodensity compared to gray matter, with a smooth, ovoid, orbital, retrobulbar mass[5][18]. Features on MRI can be more variable with orbital schwannomas, demonstrating homogenous or heterogenous enhancement and possible cystic degeneration in up to 41% of tumors[18][5] The mainstay of schwannoma treatment is complete surgical excision with attempted maintenance of capsular integrity, most commonly via an anterior orbitotomy through an eyelid crease incision[18].

For more information see: orbital schwannoma.

Neurofibroma

Neurofibromas are another less common form of nerve sheath tumor which are very similar in presentation to orbital schwannomas. They have a strong association with type 1 neurofibromatosis and also produce symptoms secondary to mass effect[5]. Similarly to schwannomas, localized neurofibromas in the orbit produce lid swelling and proptosis in up to 50% of patients, with ptosis, vision loss, and diplopia in anywhere from 4-20% of patients, however visual acuity is often preserved in the absence of optic nerve compression[18]. About 1/3 of localized orbital neurofibromas will extend into the superior orbital fissure. Importantly, localized orbital neurofibromas are not typically associated with type 1 neurofibromatosis, unless they are preceded by café au lait spots[20][18]. A few cases have been reported in which bilateral orbital neurofibromas have been found without the presence of type 1 neurofibromatosis, but the condition remains extremely rare[21][22].Neurofibromas and schwannomas in the orbit have very similar imaging findings, with a homogenous, smooth, iso- or hyperdense mass with variable enhancement.[5] They can be occasionally be differentiated from schwannomas by the absence of secondary degenerative changes (i.e. calcification). CT imaging may cause confusion between neurofibromas and cavernous hemangiomas, requiring further imaging with MRI to distinguish between the masses.[18]

Treatment of orbital neurofibroma treatment is the same as for orbital schwannomas; involving surgical excision with a similar method as described above[18][5].

For more information see: orbital neurofibroma.

Malignant Tumors

Metastasis

The most common origins of orbital metastases differ based upon the presenting age of the patients. Children tend to have orbital metastasis from neural embryonal or sarcomatous tumors, while metastases in adults tends to arise from carcinomatous tumors[23][5]. The most frequent metastases to the orbit are from breast, lung, prostate, melanoma, carcinoid, GI, renal cell, neuroblastoma, and rhabdomyosarcomas[24]. Metastasis to the ocular region occurs most commonly in the posterior part of the choroid, but orbital metastasis can be an important cause of proptosis or globe displacement in patients with a history of cancer[25]. Presenting symptoms can be highly variable and may change based on the specific type of tumor that has metastasized. In a large patient series by Shields, et al. the most common presenting sign in patients with orbital metastases was limited ocular motility, followed by globe displacement/proptosis, blepharoptosis, palpable mass, changes in vision, pain, visible mass, enophthalmos, and diplopia[25]. Enophthalmos was a specific finding for patients who were eventually diagnosed with scirrhous breast cancer metastatic to the orbit.[25]

Although MRI is better for identifying soft tissue defects, CT is typically performed for initial imaging of orbital metastases. Specific imaging findings can vary depending on the tumor etiology, and any structure in the orbit can be affected by the metastasis[5].

Lymphoma

Malignant lymphoma and reactive lymphoid lesions can both be present in the orbit, and can sometimes be grouped as “orbital lymphoid lesions[26]. These masses combined comprise between 10-15% of all orbital tumors and up to 55% of malignant orbital masses[5] Both diseases present similarly with minimal pain and mild unilateral proptosis[27][5]. Other common ocular symptoms revolving around orbital lymphoid lesions include limited eye motility, ptosis, changes in visual acuity, diplopia, chemosis/edema, and displacement of the eye[26]. Interestingly, only around 8% of patients presented in with classic B-symptoms in a large retrospective review by Olsen and Heegaard. Presentations also vary between differing types of lymphomas, with a large majority of B-cell lymphomas presenting as unilateral tumors, with other subtypes presenting unilaterally or bilaterally[26]. Any part of the orbit can be involved, with the superolateral (or “extraconal”) aspect of the orbit being most common[27][5].

Imaging studies used to aid in diagnosis of orbital lymphoma include CT and MRI of the orbit in order to identify size and anatomical location[5][27]. On imaging these masses typically appear as homogenous, lobulated masses with no erosion of adjacent bone, and can be very difficult to distinguish from orbital inflammatory disease[5]. Definitive diagnosis is made with biopsy and histopathologic review, which is necessary for proper management[27]. For more information see: orbital lymphoma.

Rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft tissue malignancy of childhood, as well as the most common primary orbital malignancy[5]. This is a life-threatening disease often seen initially by ophthalmologists, requiring prompt diagnosis and treatment[28]. While it have a predisposition for development in children younger than 8 years of age, it has been diagnosed in patients throughout adulthood, all the way up to a 78 year-old patient[29][28]. Proptosis in patients with orbital rhabdomyosarcoma can develop extremely quickly over weeks, along with rapid development of orbital displacement. Rapid proptosis tends to occur more often in newborns and infants, with older children and adults trending more towards a slower course that does not attain as large of a size. The orbital displacement in advanced cases tends to be downwards and outwards secondary to the typical supernasal involvement of these tumors[28][30]. Distant metastases are currently uncommon thanks to advances in diagnosis and treatment. If it does occur, it tends to metastasize to bone and lung through a hematogenous route rather than a lymphatic route, possibly due to the absence of lymphatics in the orbit. Local invasion of orbital bones with intracranial extension can occur, causing concern for mass effect and other symptoms[30].Most commonly, imaging is performed with CT scan after the initial signs and symptoms of an orbital mass are identified. The imaging will show a well-circumscribed, homogenous, round-ovoid mass that is isodense to muscle with moderate to marked enhancement with contrast in the early stages[28]. As the lesion progresses bone erosion and extension into the sinuses or nasopharynx may appear, occurring in up to 40% of patients. MRI can be used to aid in visualization of disease extent for assistance in surgical excision[28][5]. Importantly, fat suppression techniques are necessary to help distinguish the tumor from fat present in the orbit. Biopsy and histopathologic evaluation is necessary to establish the diagnosis before therapy is begun.Management of this disease has changed drastically in the last several decades and currently consists of a combination of surgery, irradiation, and chemotherapy. Since this is a life-threatening condition, treatment should not be delayed.[28]

For more specifics on treatment and management, please see: orbital rhabdomyosarcoma.

Optic Pathway Glioma

While optic glioma is a more uncommon orbital mass, only encompassing 1-3% of orbital tumors, it is the most common tumor of the anterior visual pathway, commonly involving the optic nerve, chiasm, tract, and optic radiations[31][5]. Lesions can be unilateral or bilateral, with bilateral involvement having a high likelihood of type 1 neurofibromatosis[31]. However, the lesions associated with type 1 neurofibromatosis tend to be more indolent when compared to the sporadic-type lesions[5]. Typically, these tumors tend to affect children less than 6 years of age. Similarly to rhabdomyosarcoma, however, cases have been reported in patients up to age 79[32]. Presentation can be widely varied and unpredictable, with symptoms including decreased visual acuity, proptosis, strabismum, nystagmus, headaches, seizures, and precocious puberty[32][31]. The majority of patients have some visual dysfunction at the time of diagnosis, regardless of the location of the lesions[32]. The most common symptoms at diagnosis in a study by Robert-Boire, et al. were headache (32.5%) followed by squinting (25.0%) and decreased vision (22.5%)[31].MRI is the most optimal imaging study for optic pathway glioma[5]. Classically, the lesions are described as sharply circumscribed fusiform thickening and tortuosity of the optic nerve, with hyperintensity on T2-weight images and widely variable enhancement. Similar to other intraorbital masses, fat suppression is necessary to best visualize the lesion if present in the orbit. Extension to the optic chiasm via the optic canal can form a dumbbell shape on imaging[5].Management of optic pathway gliomas revolves around regular clinical examinations to monitor progression of the disease[31]. Histopathologic examination typically shows low-grade tumors, and can either be described as pilocytic astrocytoma (well-circumscribed) or diffuse astrocytoma (infiltrative)[33]. Treatment is widely variable and remains one of the most challenging aspects of optic nerve gliomas. The decision is based on both patient and tumor characteristics, involving observation, surgery, chemotherapy, and radiation[31][33].

For more specific details on management of optic pathway gliomas see: optic nerve glioma.

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