Vascular Lesions of the Orbit
Susan M. Tucker
Vascular lesions of the orbit constitute approximately 11% of clinical orbital disease and 6% of orbital lesions that have undergone biopsy.1, 2 Clinical presentation is determined by the effects of the resulting hemodynamic alterations on the tissues of the orbit. Features suspicious for a vascular lesion are intermittent exophthalmos, vascular engorgement with the Valsalva maneuver, orbital pulsation or bruit, and hemorrhage. The classification of vascular tumors of the orbit has been controversial, but more recently has been better defined with advances in imaging, immunohistochemistry, and electron microscopic studies. In this chapter, vascular lesions of the orbit are classified as hamartomas, arteriovenous fistulas (AVFs), neoplasms, and “other vasculogenic masses.” Table 37.1 summarizes features of orbital vascular hamartomas: infantile capillary hemangioma, cavernous hemangioma, and orbital vascular malformations. Table 37.2 outlines characteristics of orbital neoplasms: hemangiopericytoma, malignant hemangioendothelioma, vascular leiomyoma, Kaposi’s sarcoma, epithelioid hemangioma, and Kimura’s disease. Summarizes orbital vascular malformations according to the classification proposed by the Orbital Society in 1998.3 Other vasculogenic masses consist of Kimura’s disease, ophthalmic artery aneurysm, orbital venous thrombosis, orbital hemorrhage, cholesterol granuloma, and epidermoid cholesteatoma. The very rare orbital hemangioblastoma, usually a manifestation of Von Hippel-Lindau, is discussed in another chapter.
ORBITAL VASCULAR HAMARTOMAS
Infantile Capillary Hemangioma
Hamartomas are composed of abnormal mixtures of tissue elements or an abnormal proportion of a single element that is usually present in that site. Benign hemangioendothelioma, strawberry hemangioma or nevus, and infantile or hemangioblastic hemangioma are additional terms used to describe this high-flow hamartomatous proliferation of primitive vasoformative tissues. Infantile capillary hemangioma is the most common orbital vascular tumor of childhood, estimated to occur in 1% to 2% of infants.4 It occurs predominantly in female infants, with a 3:2 female-to-male ratio most frequently reported.5, 6 Although usually sporadic, rare heritable infantile hemangiomas have been described, and may perhaps be underreported.7, 8 Predisposing factors for the development of capillary hemangiomas include maternal chorionic villus sampling9 and prematurity.10
Clinical Features
One-third of all orbital capillary hemangiomas are noted at birth, and virtually all are diagnosed by age 6 months.6 Most commonly a unilateral diffuse subcutaneous or circumscribed, dimpled, red dermal lesion (strawberry nevus) is noted on the upper eyelid (Figs. 37.1 and 37.2).5, 6 In more than one-third of patients, the palpebral or fornical conjunctiva is involved.6 Commonly, this superficial lesion is associated with a component deep to the orbital septum, resulting in variable degrees of proptosis in 38% of patients.6 More rarely, it can occur as an isolated lesion posterior to the orbital septum without a superficial component. In Haik and colleagues’6 large series of 101 infants with capillary hemangiomas, seven presented with proptosis alone. Forty-six percent of patients have an increase in lesion size with crying or Valsalva maneuver.6 Early flat, circumscribed lesions rapidly expand into bulky, compressible masses over a period of weeks to months as the capillary lumina of the endotheliomatous hamartoma opens. This distinguishes the capillary hemangioma from the port-wine stain (nevus flammeus) associated with the Sturge-Weber and Klippel-Trenaunay syndromes, which remains flat to slightly thickened and is noncompressible. The infantile capillary hemangioma usually reaches its largest size within 6 months and then typically involutes.6 Fine, stellate areas of pale scarring (herald spots) appear during resolution (Fig. 37.3). Residual pigmentary skin changes and superficial cutaneous scarring may result.6 The most common ocular complication of adnexal capillary hemangiomas is visual loss, most often resulting from amblyopia or in rare cases optic atrophy. Amblyopia occurs in 27% to 64% of these infants and is most frequently a result of anisometropia, but also of visual deprivation from occlusion of the pupil, or both.5, 6, 11 Anisometropia may result from axial myopia induced by the eyelid closure or astigmatism (plus cylinder axis points toward the tumor mass).12 The risk of amblyopia increases with the size of the lesion and location; 64% with nasal lesions versus 27% with temporally located lesions.11 In a review of 129 patients with 132 capillary hemangiomas, Schwartz and colleagues11 found strabismus in 15% of patients.
TABLE 37-1 Vascular Tumors of the Orbit: Hamartomas | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Ultrasound | CT | ||||||||||
Lesion | Test(s) if Suspect | IR | IS | SA | Typical | Calcification | MRI (Compared to Gray Matter) | Angiography | Encapsulated | Natural History | Management |
Infantile capillary hemangioma | Clinical diagnosis ± enhanced MRI | High and low | Irregular | Moderate | Well-defined to irregular margins; intraconal/extraconal; moderate to intense enhancement ± globe indentation ± orbital bony enlargement | No | T1: Isointense | Multiple feeding vessels ICA, ECA | No | Complete resolution up to 60% age 4 y and 76% age 7 y | ± Oral propranolol ± Intralesional steroids ± Systemic steroids, surgery, cryotherapy, laser, interferon, selective arterial embolization |
Cavernous hemangioma | Enhanced CT | High | Regular | Moderate | Oval or rounded intraconal mass; progressive homogeneous or inhomogeneous enhancement ± globe indentation ± orbital bony enlargement | Rarely | T1: Isointense T2:Hyperintense Spread pattern | Not indicated | Yes | Slowly enlarge | ± Surgical excision |
Orbital vascular malformations | |||||||||||
• No flow/lymphatic | Unenhanced MRI | Low | Regular | Marked | Poorly defined intraconal/extraconal mass with rim enhancement ± global indentation ± orbital bony enlargement | Yes | T1: Hypointense ( lymphatic cyst) Hyperintense ( hemorrhagic cyst) T2: Hyperintense | No | Slowly enlarge until adulthood; spurts of growth with RTI and hemorrhages | ± Sclerotherapy ± Surgical debulking | |
• Venous/venous lymphatic | Spiral CT MRI | Low | Regular | Minimal | Dilated/lobular uniform enhancement | Yes, 45% | Uniform enhancement T1: Hyperintense T2: Hyperintense | Essential prior to surgery | No | Slowly enlarge | ± Sclerotherapy ± Embolization ± Surgery |
• Arterial flow | MRA ± Angiography | Irregular rapidly enhancing mass | Rapid enhancement | Essential prior to surgery | No | Slowly enlarge | ± Embolization with surgery | ||||
IR, internal reflectivity; IS, internal structure; SA, sound attenuation; ICA, internal carotid artery; ECA, external carotid artery; RTI, respiratory tract infection. | |||||||||||
TABLE 37-2 Vascular Tumors of the Orbit: Neoplasias | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Ultrasound | CT | ||||||||||
Lesion | Test(s) If Suspect | IR | IS | SA | Typical | Calcification | MRI (Compared to Gray Matter) | Angiography | Encapsulated | Natural History | Management |
Hemangiopericytoma | CT or MRI ± cerebral angiography | Low to medium | Regular/slightly irregular | Mild to moderate | Oval or rounded extraconal superior mass; intense early enhancement ± orbital bone erosion | Yes | T1: Isointense T2: Isointense Heterogeneous enhancement | Intense blush; multiple feeding vessels | Pseudocapsule | Aggressive local behavior ± distant metastases | ± Surgical excision |
Malignant hemangioendothelioma | CT or MRI ± cerebral angiography | Irregular | Circumscribed or infiltrative orbital mass; intense early enhancement ± orbital bone erosion | Pseudocapsule | Aggressive local behavior ± distant metastases | Surgical excision | |||||
Vascular leiomyoma | Enhanced MRI | Intraconal mass | T1: Isointense T2: Hyperintense | Yes | Slowly enlarge | Surgical excision | |||||
Kaposi’s sarcoma | Clinical ± fluorescein angiography | No | Slowly enlarge | ± Surgical excision, cryotherapy, radiotherapy Intralesional chemotherapy Systemic chemotherapy | |||||||
Epithelioid hemangioma | Excision ± radiotherapy | ||||||||||
Kimura’s disease | No | Surgical excision ± radiotherapy | |||||||||
IR, internal reflectivity; IS, internal structure; SA, sound attenuation; ICA, internal carotid artery; ECA, external carotid artery; RTI, respiratory tract infection. — | |||||||||||
 FIG. 37.1 Capillary hemangioma. Eight-month-old patient with a diffuse subcutaneous lesion of the left superior orbit, with a component deep to the orbital septum. Note the displacement of the globe inferiorly. (Courtesy of Dr. Nancy A. Tucker, University of Toronto.) |
 FIG. 37.2 Capillary hemangioma. Six-month-old patient with a circumscribed, red, dimpled dermal “strawberry nevus” capillary hemangioma. This patient had resolution of the induced astigmatic anisometropic refractive error after one intralesional steroid injection. |
Associated dermal or laryngeal have been reported,6 and more rarely hepatic, gastrointestinal, or intracerebral hemangiomas may be present.13 Sequestration of platelets and red blood cells leading to thrombocytopenia and bleeding diathesis (Kasabach-Merritt syndrome) can occur with large visceral lesions, but are rare with isolated head and neck lesions.14
Investigations
Most capillary hemangiomas can be diagnosed readily by clinical inspection. However, if delineation of the extent of deep orbital involvement is required, or the diagnosis is unclear, magnetic resonance imaging (MRI) with surface coils, gadolinium-pentetic acid enhancement, and fat suppression (to detect enhancement against the orbital fat) is indicated. The tumor is isointense to muscle and gray matter on T1-weighted images, and hyperintense on T2-weighted images.15 The enhancement seen with intravenous contrast varies from moderate to intense and may be homogeneous or inhomogeneous.6 Lesions undergoing involution are less intense and more inhomogeneous. Major feeding vessels appear as black, serpiginous structures because of the “flow void” phenomenon.15 B-scan ultrasonography shows a smooth, lobular, or irregular mass with variable internal reflectivity that blends into surrounding orbital structures. A-scan ultrasonography shows alternating high internal reflectivity (high echo spikes) and low internal reflectivity (low echo spikes) resulting from the variable architecture and acoustic interfaces of vascular spaces, cellular areas, and septa, and moderate sound attenuation.16 High vascular flow may be demonstrated on Doppler echography. On computed tomography (CT) scan, the margins of deep infantile hemangiomas vary from moderately well defined to irregular.17 They can occur anywhere within the orbit and may be both intraconal and extraconal. Very rarely, hemangiomas can occur within the extraocular muscles.18 There are no calcifications within these lesions. Occasionally, they indent the globe and are associated with bony orbital enlargement without erosion.6 Very rarely, angiography may be needed in the unusual situation where hazardous superselective embolization is used for life-threatening hemangiomas unresponsive to other therapies.13 These lesions frequently have multiple feeding vessels from both the internal and external carotid arteries.
Histopathology
Infantile capillary hemangiomas are unencapsulated lesions composed of masses of plump proliferating endothelial cells which line blood-filled vascular channels interspersed with fibrous septa (Fig. 37.4).6 A reticulin stain may help delineate primitive vascular structures in early stages of proliferation when there are few vascular spaces.6 During the proliferative phase or for poorly differentiated tumors, the localization of von Willebrand factor produced by the endothelial cells by either peroxidase or fluorescent antibody technique may prove useful.6 Lesions undergoing involution are characterized by fewer endothelial cells, larger and less numerous vascular channels, increasing collagen deposition, intralesional fat, and in some instances, inflammatory cell infiltrates. The late regression phase is dominated by fibrosis.6
 FIG. 37.3 A: Patient with capillary hemangioma at age 2 months. B: Patient at age 5 months, 8 weeks after intralesional steroid injection. Note the stellate areas of pale scarring (herald spots) characteristic of the resolution phase of this lesion. |
Differential Diagnosis
The differential diagnosis of a rapidly expanding orbital mass in infancy and early childhood includes rhabdomyosarcoma, chloroma, neuroblastoma, vascular malformations, congenital hydrops of the nasolacrimal sac, dermoid cyst, and orbital cellulitis.
 FIG. 37.4 Infantile capillary hemangioma. Characteristic pattern of masses of plump endothelial cells organized into a network of basement membrane-lined vascular channels with small, irregular lumina. Red blood cells are present within these spaces (H&E, ×250). |
MANAGEMENT
Natural History
Outlining the natural history of these lesions to the parents is extremely important in alleviating their concerns and anxieties and in justifying the usual decision for conservative management. The rate of complete resolution without treatment is 32% to 60% at 4 years of age, and 72% to 76% at 7 years of age; there is variable improvement in the remaining children until the age of 10 to 12 years.19
Treatment
Treatment is required for children with refractory amblyopia, threatened occlusion of the visual axis, compression of the optic nerve, or corneal exposure secondary to severe proptosis. Controversy exists about the most appropriate management of induced astigmatism and anisometropic refractive error, with some authors advocating early treatment to reverse severe refractive errors.6, 20 Nonvisual indications for therapy include deep lesions that bleed frequently, secondary maceration and erosion of the epidermis, or severe disfigurement. Systemic indications for treatment are cardiovascular, hematologic, or obstructive complications.13
Intralesional corticosteroids have been the mainstay of initial therapy in lesions requiring treatment, although more recently, favorable results using oral propranolol have been reported.21, 22 Both appear efficacious in reducing astigmatism and spherical equivalents of refractive error, but objective data from prospective randomized trials are needed to determine relative efficacy and side effects of these two treatment modalities. In 2008, successful treatment of severe infantile hemangiomas with oral propranolol was noted incidentally when used to treat high-output cardiac failure.21 Potential explanation for the therapeutic effect of propranolol, a nonselective betablocker, includes vasoconstriction, decreased expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), and triggering apoptosis of capillary endothelial cells.21 A recent literature review found that oral propranolol was the first-line treatment in 50/85 (58.8%) of patients. The commonest dose was 2 mg/kg/day in three divided doses per day, often titrated up from 0.5 to 1 mg/kg/day. The youngest child treated was 1 week of age, and the oldest 18 months, with a mean age of 4.8 months. Duration of treatment varied between 2 weeks and 1 year, with mean duration of 6.9 months. Improvement or complete resolution was reported in 96% of cases. Adverse effects occurred in one-third of cases, but most of these were minor. In the remaining 4%, propranolol was discontinued due to hypotension, bradycardia, asthma onset, hypoglycemia, or no effect on astigmatism. Recurrences developed in one-fifth of cases.22
The therapeutic effectiveness of intralesional steroids results from arteriolar constriction and narrowing of precapillary sphincters.23 Combinations of short- and long-acting corticosteroids of various doses have been successful. Generally, the long-acting depot steroid is directed deep into the lesion to prevent deposits from being visible under the skin, and the more soluble short-acting corticosteroid is given subcutaneously around the periphery of the capillary hemangioma. Injections usually are given under mask inhalation; separate 1- to 3-mL syringes with 25G or 27G needles are used for each substance. The following are two popular regimens: (a) 40 mg triamcinolone acetate and 6 mg betamethasone given separately into the lesion24 or (b) 40 mg methylprednisolone and 4 mg dexamethasone sodium phosphate given separately into the lesion.5 Some authors vary the dose according to the size of the capillary hemangioma.25, 26 Involution of the tumor may begin several days after injection and usually is considerable within 2 to 4 weeks.20 Injections can be repeated at 6-week intervals, as needed.5, 26 Intralesional corticosteroids are effective in inducing moderate to marked involution in 45% to 88% of cases,13, 20, 26 but recurrence and regrowth with diminution of the steroid dose is not infrequent. Potential complications of intralesional steroids include adrenal suppression, blindness secondary to retinal embolization of the corticosteroid, eyelid depigmentation, eyelid necrosis, and subcutaneous fat atrophy.27, 28
Other treatment modalities include topical steroids, sub-Tenon infusion of steroids, systemic corticosteroids, surgery, cryotherapy, laser therapy, interferon injections, and selective arterial embolization.13, 29, 30 and 31 Topical clobetasol propionate cream given twice daily for 2 weeks, with 1 week drug-free periods, may be an alternative mode of treatment in those patients whose parents decline intralesional steroids.31 Early surgical intervention in infants 2 to 20 months for selected hemangiomas without a significant cutaneous component has been reported with good results.17, 29, 32 Preoperative radiologic tests (magnetic resonance angiogram, arteriogram, or digital intravenous arteriogram) and blood typing are advisable for all patients. A true capsule is not present,29 making complete surgical excision of extensive infiltrating lesions very difficult. When surgery is performed in patients with Kasabach-Merritt syndrome (very large platelet-consuming lesions), systemic antifibrinolytic agents are needed, including aminocaproic acid or tranexamic acid. Tronina and colleagues reported good cosmetic and anatomic results in 90.4% of 174 children aged 1 to 16 months (mean 5.2 months) treated with cryosurgery of superficial intradermal lesions and surgical excision of subdermal/orbital components. Only one cryosurgical procedure was needed in 63.1% of cases, but ranged from one to five cryosurgeries.33 Interferon alfa, which inhibits both endothelial cell and fibroblast proliferation, has been used for life-threatening hemangiomas resistant to corticosteroids. 34,35 Hastings and colleagues examined 40 patients aged 2 to 36 months with life- or organ-threatening hemangiomas treated with daily subcutaneous interferon alfa-2b for 3 months, followed by taper or retreatment. An average 82% reduction in tumor volume occurred, with clinical response observed at an average of 6 weeks.35
Therapeutic arterial embolization is particularly hazardous and has yielded inconsistent results; it is therefore a last resort for life-threatening situations.13
Cavernous Hemangioma
Cavernous hemangiomas are benign, noninfiltrative, low-flow hamartomas. Although often cited as the most common primary orbital tumor of adults,4, 6 in the largest reported series from Moorfields Eye Hospital, cavernous hemangiomas constituted only 7% of 1,270 patients with primary orbital tumors and were outnumbered by venous flow malformations (VFMs) by a ratio of 3:1.36
Clinical Features
Patients typically present in the fourth and fifth decades, although the age range spans from occasional case reports in children younger than 18 years of age37 to an adult 78 years old.38 A 60% to 70% female preponderance is reported consistently.6, 36, 39 Seventy percent of patients present with gradually increasing painless proptosis, which usually is axial.6, 39 Less common symptoms of orbital pain, eyelid swelling, diplopia, and gaze-induced amaurosis can occur.36, 39, 40 In a series of 162 cavernous hemangiomas (110 histologically proven), no episodes of acute or subacute hemorrhage were documented.41 Cavernous hemangiomas appear to enlarge by proliferation of capillaries,6 and local hemodynamic disturbances, hypoxia, and hormonal changes during pregnancy may stimulate their growth.6 On clinical examination, other signs of mass effect may accompany the proptosis: In their series of 85 patients, McNab and Wright36 reported 32% with posterior pole choroidal striae and 16% with compressive optic neuropathy. Orbital cavernous hemangiomas usually are isolated lesions. Very rarely, they may be associated with multiple hemangiomas involving predominantly the arms and trunk (usually evident at birth) and visceral lesions commonly in the small intestine, leading to gastrointestinal bleeding and iron deficiency anemia (the blue rubber bleb nevus syndrome).42
Investigations
Contrast-enhanced CT of the orbits with direct and coronal cuts is the radiologic study of choice for these patients.39 A well-demarcated, encapsulated oval or rounded mass is revealed, which is typically intraconal in the lateral part of the middle third of the orbit (Fig. 37.5), but occasionally may extend to the extraconal space.36 Septa within the tumor may be apparent on high-resolution CT. The posterior pole of the globe frequently is indented by the rounded anterior margin of the tumor.36 The optic nerve typically is displaced rather than surrounded by the tumor. Subtle outward bowing of the lateral orbital wall or increase in orbital size may be present, consistent with a long-standing, slowly growing mass lesion.6, 36 Enhancement with intravenous contrast occurs and may be homogeneous or inhomogeneous.6, 39 Rarely, cavernous hemangiomas may occur as an intraosseous tumor within the orbital or facial bones.36, 43, 44 Although usually an isolated intraorbital lesion, multiple lesions in one orbit occurred in 8 of 164 (5%) patients of three combined large studies,6, 36, 39 and bilateral multiple cavernous hemangiomas also have been described.45 In contrast to patients with VFMs in which phleboliths are common, phleboliths are rare in cavernous hemangiomas. Three large studies comprising 164 patients with cavernous hemangioma all reported that no calcification was detected within the tumor.6, 36, 39 If the diagnosis is still unclear or if better definition of details and localization of the lesion is required, then MRI should be performed. MRI demonstrates nonspecific characteristics of a lesion isointense to muscle and gray matter on T1-weighted images and hyperintense on T2-weighted images (Fig. 37.6).46 Contrast-enhancement spread pattern in dynamic MRI scans (starting from one point or portion, rather than a wide area) allows differentiation from schwannoma (heterogeneously isointense or mildly hyperintense), neurofibroma, or meningioma.47, 48 If ultrasonography is performed, B-scan ultrasonography shows a well-circumscribed mass with a sharply defined anterior acoustic border. A-scan ultrasonography shows high reflectivity of the echo signals resulting from the multiple blood-filled vascular channels, regular internal structure with a higher anterior and posterior spike marking the capsule, and moderate sound attenuation (angle of decrease of the echo spike within the lesion).16
 FIG. 37.5 Cavernous hemangioma. Contrast-enhanced axial CT scan shows a well-demarcated, oval intraconal mass in the lateral part of the middle third of the orbit. Note the enhancement within the lesion, which in this instance is inhomogeneous, but can also be homogeneous. |
Histopathology
Histopathology reveals large, endothelium-lined, blood-filled spaces separated by fibrous septa and surrounded by a fine capsule (Figs. 37.7 and 37.8). Abundant, loosely distributed smooth muscle is present in the vascular walls, and scattered inflammatory cells may be seen.6, 38 Histopathologic confirmation of the low-flow character of this lesion is seen by the presence of menisci in some vascular spaces and evidence of decomposed blood.
Differential Diagnosis
The differential diagnosis of cavernous hemangioma includes neurofibroma, cystic schwannoma, fibrous histiocytoma, and vascular leiomyoma. Hemangiopericytoma, hemangioendothelioma, and cystic schwannoma can have similar ultrastructural features.39 Osseous hemangioma usually can be distinguished from meningioma by the lack of extensive hyperostotic changes and from osteosarcoma, multiple myeloma, and metastatic cancer by the absence of irregular bone destruction.
 FIG. 37.6 Cavernous hemangioma. Axial MRI demonstrates a well-defined, homogeneous intraconal mass that is isointense to muscle and gray matter on T1-weighted image (A), and hyperintense on T2-weighted image (B). Note the displacement of the optic nerve and indented posterior globe. |
 FIG. 37.7 Cavernous hemangioma. Gross cut specimen showing large blood-filled spaces separated by fibrous septa and surrounded by a fine capsule. (Courtesy of Dr. Seymour Brownstein, University of Ottawa.) |
 FIG. 37.8 Cavernous hemangioma. Histopathologic appearance of the widely dilated vascular spaces filled with red blood cells. Abundant, loosely distributed smooth muscle is present in the vascular walls, and scattered inflammatory cells can be seen (H&E, ×100). |
MANAGEMENT
Natural History
The natural history of cavernous hemangiomas is to enlarge,6 but in the absence of symptoms or visual compromise, observation of asymptomatic cavernous hemangiomas is reasonable.
Treatment
Treatment, when indicated, involves surgical excision of the lesion. Blunt dissection reveals a plump, nodular, plum-colored, encapsulated mass with vascular channels on its well-defined surface. Because of its low-flow character, a cavernous hemangioma can be punctured during surgery, leading to exsanguination and shrinkage of the tumor, which facilitates its removal.36 A cryoprobe may assist with extraction. If an apical vascular tag can be identified, it should be cauterized; otherwise the gush of blood when it is transected can be controlled with gentle tamponade.
The risks of surgery depend on the location of the hemangioma within the orbit: removal at the orbital apex can be challenging. The degree of fusion between the tumor capsule and visually important structures may be the most critical determinant of surgical outcome, and “inoperative” attachment may mean incomplete removal. Although the transcranial approach is optimal for tumors of the superomedial orbital apex, inferior and inferomedial apical cavernous hemangiomas are more accessible from a transnasal approach.49, 50 Reports of postoperative complications from nonapical tumors vary greatly. Lumping together 4 apical and 21 nonapical intraconal hemangiomas, Missori and colleagues51 found no complications in the two patients operated on transorbitally, but permanent ptosis in 3/23 (13%), permanent “visual worsening” in 8/23 (62%), and ophthalmoplegia in 4/23 (17%) of patients operated on transcranially. Two of four apical tumors operated on by Missori and colleagues51 via a transcranial approach developed “complete amaurosis.” Kersten and Kulwin described 37 surgeries for removal of orbital hemangiomas (location within orbit not given); 35 removed via orbitotomy and 2 via craniotomy. One patient suffered “reduction in visual acuity,” and limitation of extraocular motility occurred in two patients.52 Gdal-On and Gelfand reported on 12 patients with hemangiomas confined mainly to the middle third of the orbit (no apical tumors) undergoing cryosurgical extraction from a 360-degree conjunctiva peritomy. One patient lost vision because of intraoperative cilioretinal arterial occlusion; there were no complications in the remaining 11 patients.53 Pelton and Patel described five intraconal cavernous hemangiomas removed via a superomedial lid crease approach. One patient had transient vertical diplopia for 2 months, and two patients had transient ptosis for 2 and 6 weeks.54 Full preoperative disclosure of potential risks is important, including profound vision loss, diplopia, ptosis, corneal anesthesia, pupillary abnormality, and loss of accommodation. A few surgically inaccessible hemangiomas involving the cavernous sinus have been treated successfully with stereotactic radiosurgery55 and gamma knife surgery.56
ORBITAL VASCULAR MALFORMATIONS
In 1998 the Orbital Society, consisting of oculoplastic and orbital surgeons from North America, Europe, and Australia, devised a nomenclature of classifying orbital vascular malformations according to their hemodynamic relationships as no flow, venous flow, and arterial flow lesions.3 It was the consensus that this hemodynamic classification was more germane to clinical management than purely morphologic differentiation. Despite this, multiple terminology continues to exist in more recent publications.
No Flow/Lymphatic Malformations
The term no flow/lymphatic malformation (NFLM) is appropriate when hemodynamic isolation is demonstrated: that is, the lack of connection of the lesion to the arterial or venous system on imaging studies. These lesions, also referred to as lymphangiomas orlymphatic malformations, presumably arise embryologically from misdirected vascular anlage tissue capable of differentiating into lymphatics, blood vessels, and other mesodermal elements. A spectrum of resulting lesions exists, with hybrid forms composed of combinations of lymphatic and vascular elements.57
Clinical Features
NFLMs have been reported in a ratio of females to males 1:158 to 1.4:1.57 Most are noted at birth (59%), often presenting as a unilateral swelling or periorbital mass,58 65% present in the first decade, and 92% by the end of the third decade.41 The channels of an NFLM are fully formed at birth, but the lesion can remain inconspicuous until it expands. Lesions may: (a) have purely superficial, multicystic conjunctival (Fig. 37.9) or eyelid involvement; (b) be localized deep within the orbit; or (c) have both superficial and deep components. Superficial lesions on the eyelid and conjunctiva transilluminate and may appear bluish because of xanthochromic or partially blood-filled cysts.59 Deep lesions can be massive, involving the intraconal, extraconal, preseptal, and postseptal spaces, often resulting in significant cosmetic disfigurement. In a review of 42 patients, 22% percent of lesions were intraconal, 30% were extraconal, and 48% combined.58 There are no clinical features of either arterial or venous connection; that is, Valsalva maneuver and alteration of head position do not produce a change in lesion size, and there is no bruit or pulsation.57 Expansion during upper respiratory infections presumably results from lymphoid hyperplasia in response to immune challenge.60 Bleeding likely results from the rupture of fine blood vessels that course through the flimsy septa of the lymph channels. Clinically, these episodes of expansion manifest as acute proptosis, ptosis, restricted motility, periorbital ecchymosis and swelling, and subconjunctival hemorrhages.57, 61 Shrinkage of blood cysts usually occurs over a period of several weeks to several months.57 The probability and timing of future orbital hemorrhage are highly unpredictable. In a study of 42 patients, 52% had intralesional bleeding, and 26% had a history of infection.58 In a study of 30 patients diagnosed with NFLM, 40% of patients managed without surgery had additional hemorrhages 2 weeks to 11 years later; 52% of patients who underwent orbitotomy for debulking had additional hemorrhages 4 days to 12 years later.57 Visual loss may result from anisometropic amblyopia, optic nerve compression, or exposure keratopathy from extreme proptosis.57 Associated ipsilateral congenital ocular malformations also may be present, including congenital ptosis, congenital strabismus, microcornea, sectorial cataract, heterochromia irides, and abnormal iris vessel.57, 59 In Greene’s review of 42 patients, 76% had intermittent swelling, 52% ptosis, 45% proptosis, 33% amblyopia, and 7% became blind in the affected eye.58 Extraorbital extension was present in more than one-half of patients (the most common sites were cheek, temporal area, and frontal lesions), and 45% had an associated cerebral venous anomaly.58 Orbital involvement is almost always unilateral. When bilateral involvement exists, the rare entity of generalized lymphangiomatosis with cystic lesions in visceral organs and lytic bone lesions should be suspected.62
 FIG. 37.9 No flow/lymphatic malformation of the orbit. Conjunctival mass with multicystic structures containing serous fluid and an admixture of blood and blood products. (Courtesy of Nancy A. Tucker, MD, University of Toronto.) |
 FIG. 37.10 A and B: No flow/lymphatic malformation of the orbit. Sagittal MRI showing dilated cystic spaces hypointense to muscle on T1-weighted images (A) and hyperintense to muscle on T2-weighted images (B). |
Investigations
If NFLM is suspected, MRI should be ordered of the orbits and brain to exclude noncontiguous intracranial anomalies.63 MRI demonstrates the dilated cystic spaces with either a hypointense (lymphatic cyst) or hyperintense (hemorrhagic cyst) signal on T1-weighted images, and a hyperintense signal on T2-weighted images (Figs. 37.10A and B).64 Layering may be seen within the cysts if there has been a recent hemorrhage leaving unreabsorbed blood. The CT scans of patients with a deep NFLM show lowdensity, poorly defined masses behind the orbital septum in the extraconal and intraconal spaces, which may indent the globe.61 Calcification within the mass (Fig. 37.11) and inhomogeneous enhancement of the rim and focal areas within the lesion may be seen that correspond to abnormal endothelially lined channels.61 Enlargement of the bony orbit can occur, particularly with combined lesions.57, 61 If the diagnosis is still unclear, ultrasonography can be performed. A cystic orbital mass is seen on Bscan. A-scan shows features of a solid, cellular tumor: low reflectivity, regular homogeneous internal structure, and marked sound attenuation through the mass.57, 61 Standard pulsed Doppler ultrasound confirms no intrinsic flow within the lesions.
 FIG. 37.11 Axial CT scan of patient in Figure 37.9, showing poorly defined orbital mass with calcifications. (Courtesy of Nancy A. Tucker, MD, University of Toronto.) |
Histopathology
Histopathology consists of nonencapsulated networks of thin-walled, dysplastic, serous-containing vessels.65 The absence of lymphocyte aggregates does not preclude the diagnosis.57 Smooth muscle cells and pericytes may be identified within the septa, suggesting that some of the channels are vascular in nature.61
Differential Diagnosis
The main clinical and histologic differential diagnosis of an NFLM is a VFM. Clinical and imaging evidence for a lack of continuity with the systemic vascular system is required to differentiate between the two entities. The superficial component of an NFLM generally is more striking, with evidence of varying types of tortuous vascular channels, some of which contain blood, menisci, or clear fluid, compared with the larger, blood-filled channels of a VFM. NFLMs may be associated with expansion during intercurrent illness, and similar lesions may be seen elsewhere in the skin and mucous membranes of the head and neck. Other causes of recurrent and intermittent exophthalmos are neurofibromatosis, ruptured dermoids, orbital hemorrhage, and ethmoiditis.
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