Ординатура / Офтальмология / Английские материалы / Retinal Vascular Disease_Joussen, Gardner, Kirchhof_2007

c

Fig. 28.1.9. Combined hamartoma of the RPE and retina. a Ophthalmoscopic appearance of an elevated, well-circumscribed amelanotic lesion adjacent to the optic nerve head. b Arterial phase of fluorescein angiography reveals spidery vasculature within the lesion. c Later frames reveal hyperfluorescence and leakage

during arterial and early venous phases (Fig. 28.1.9b). Late frames disclose leakage and hyperfluorescence of the tortuous intralesional vasculature (Fig. 28.1.9c). The lesion is hyperreflective and elevated on optical coherence tomography, with hyporeflective shadowing posteriorly [78].

Though approximately 10 % of reported cases are found on routine examination of asymptomatic patients, the majority of patients present with painless visual loss. Thirty to 45 % of cases have initial presenting visual acuities of 20/40 or better, but 30 – 40 % had visual acuity of 20/200 or worse on first presentation [20, 62]. Decreased visual acuity leads to strabismus in 20 – 25 % of patients, usually children [20, 62]. Uncommon presentations include leukocoria, floaters, and pain [62]. Visual loss may occur with direct involvement of the optic nerve, macular, or papillomacular area, epiretinal membrane formation, or retinal folds. Uncommonly, these hamartomas may cause vitreous hemorrhage

[14, 37, 55, 83], choroidal neovascularization [18, 31, 62, 75], preretinal neovascularization [29], lipid exudation [62] or macular holes [53, 80].

Isolated epiretinal membrane may be considered in the differential diagnosis of combined hamartomas, as these may also be associated with vascular tortuosity and vitreoretinal interface changes. However, isolated epiretinal membranes are rarely pigmented. Other elevated, pigmented fundus lesions, such as congenital hypertrophy of the retinal pigment epithelium, choroidal nevi and choroidal melanoma, may also be confused with combined hamartomas, though these are usually not associated with vascular tortuosity and vitreoretinal interface changes, and typically do not involve the retinal layer. When choroidal melanomas are advanced enough to involve the retina, they are usually much thicker than the typical thickness of combined hamartomas.

Histopathology of combined hamartoma of the retinal pigment epithelium and retina

Histopathologically, retinal glial proliferation and disorganization of retinal architecture is common [82] (Fig. 28.1.10a). In peripapillary lesions, vascular proliferation and hyperplastic RPE cause thickening of the optic nerve head and surrounding retina. Vascular tortuosity may occur as a result of retinal layer disturbances, but abnormal capillary proliferation is also present [45] (Fig. 28.1.10b). Proliferation of the retinal pigment epithelium is often found surrounding blood vessels (Fig. 28.1.10c). The proliferating RPE often extends into the inner retinal layers, and may be present in preretinal fibrovascular tissue [25]. Vitreous condensation often overlies the lesions. Infiltration of the optic nerve by retinal pigment epithelial cells has been reported in juxtapapillary hamartomas [74].

With an average 4-year follow-up period, approximately 65 % of patients retained visual acuity within 2 lines of presenting visual acuity [62]. However, 20 % lost 2 or more lines of vision. Epiretinal membranectomy may improve visual acuity [53, 61, 62,

Essentials

Congenital retinal arteriovenous malformations

May be associated with Wyburn-Mason syndrome

Large vessels with variable wall thicknesses occupy the entire thickness of the retina

Racemose hemangiomas, also known as cirsoid aneurysms and congenital retinal arteriovenous communications, are enlarged vessels that connect and shunt blood from the retinal arterial to the retinal venous circulations (see Chapter 26.2). These are usually unilateral, are equally common in men and women, and are rarely hereditary [50]. Approximately 25 – 30 % are associated with Wyburn-Mason syndrome, in which intracranial AV malformations are present, usually ipsilateral to the racemose hemangioma [50, 76] (see Chapter 26.2).

The retinal arteriovenous communications have a wide range of clinical manifestations. In the mildest form, the lesions may appear as small, tortuous, peripheral arteriovenous communications or can

Fig. 28.1.11. Wyburn-Mason syndrome. Dilated, tortuous vessels emanate from the optic nerve head

appear as slightly enlarged retinal vessels that cross the horizontal midline. Patients may be asymptomatic at this stage. Larger lesions consist of dilated vessels emanating from the disk that follow a tortuous path through the fundus (Fig. 28.1.11). No spontaneous pulsation is seen [20]. Most lesions are found in the temporal quadrants or near the papillomacular bundle [50].

Visual loss is present in the majority of patients with large lesions, and may be secondary to optic nerve, retinal or intracranial involvement by these

744

28 III

become associated with sub-RPE and choroidal neovascularization, forming retinal-choroidal anastomoses [27, 40, 70]. Intraretinal hemorrhages seen at all stages may distinguish this form of neovascular ARMD [17, 86]. These lesions tend to be bilateral, with symmetric involvement [86]. Affected individuals are much more likely to be Caucasian and over the age of 80 [86]. Women are also more likely to be affected.

Clinically, RAP can be divided into three distinct stages. Stage I, or intraretinal neovascularization, is the earliest form of RAP [86]. The patient may be asymptomatic. A mass composed of angiomatous vasculature is present within the middle and inner retina, associated with intraretinal hemorrhages and edema. Occasional retinal-retinal anastomoses may be seen. Fluorescein angiography is notable for focal intraretinal leakage corresponding to the area of neovascularization and retinal edema [86].

Stage II, or subretinal neovascularization, occurs when the intraretinal neovascularization has extended to involve the space between the RPE and the photoreceptor layer. Clinically, these eyes have more tangential branching of the vasculature in the subretinal space, an increase in retinal edema, and a localized retinal detachment in the area of subretinal neovascularization. If neovascularization reaches or fuses with the RPE, a serous pigment epithelial detachment is usually seen. Subretinal, intraretinal, or preretinal hemorrhages may be seen. Retinal-retinal anastomoses are more common. Fluorescein angiography reveals diffuse intraretinal and subretinal leakage in the area of the lesion, making this difficult to differentiate from occult choroidal neovascularization; however, a hot spot on the indocyanine green (ICG) angiogram corresponding to the area of neovascularization can be seen [17].

Stage III, or choroidal neovascularization, occurs when both choroidal and retinal neovascularization are present. Retinal-choroidal anastomosis is presumed to have formed in such cases, though this may be difficult to detect clinically. Choroidal neovascularization usually appears more robust than the intraretinal or subretinal neovascular components. Disciform scarring may be present. Leakage in the sub-RPE and subretinal spaces occurs on fluorescein angiography. In the late phase of ICG angiography, RAP lesions become more hyperfluorescent since most of the dye remains intravascular. Unlike occult CNV, RAP does not exhibit a late washout effect [17]. Optical coherence tomography (OCT) can be used to demonstrate the intraretinal neovascular complex in cases of indistinct FA and ICG angiography [88].

RAP is most often misdiagnosed as occult or minimally classic choroidal neovascularization associated with ARMD, as it appears similar on fluorescein angiography. Unlike RAP, occult and minimally classic

CNV are rarely associated with small intraretinal or preretinal hemorrhage and it is rare to see retinal perfusing or draining vessels. The characteristic “hot spot” on ICG angiography is well demarcated in RAP; in isolated CNV, ICG dye may leak extensively into subretinal or sub-RPE spaces. The ICG hot spot due to RAP may be difficult to differentiate from polypoidal

CNV or focal occult CNV unless the CNV is associated III 28 with exudative detachment and the isolated choroidal

nature of neovascularization in those lesions can be distinguished, or unless the RAP lesion has a distinct anastomotic connection between the retina and choroid. ICG hot spots may also be confused with retinal macroaneurysm or small capillary hemangiomas. In some cases, associated macular edema and small intraretinal hemorrhages may be confused with branch retinal vein occlusion [17].

Histopathology of retinal angiomatous proliferation

Histopathologic examination of six lesions obtained by submacular membranectomy [44] disclosed subretinal fibrovascular membrane with retinal pigment epithelium, basal deposits, and degenerated photoreceptor outer segments scattered in amorphous proteinaceous material (Fig. 28.1.14). A fibrocellular membrane within Bruch membrane was present in some lesions, associated with disruption of the basal deposit. In others, large vessels leaving the subretinal fibrovascular membrane extending toward the neurosensory retina were seen. The neurosensory retina was detached in most lesions, although outer neurosensory retina was firmly adherent to the subretinal fibrovascular tissue in some cases. The authors contrast this to occult and classic CNV lesions, which tend to remain adherent to the choroid. No CNV or retinalchoroidal anastomosis was found [44]. However, this study cannot confirm the histopathologic existence of RAP, as lesions were not sectioned in their entirety, and no intraretinal neovascularization extending into the subretinal space was documented. No other studies with confirmatory histologic evidence have been published. This will likely be possible only with detailed study of the whole eye.

Fig. 28.1.14. Retinal angiomatous proliferation. Submacular membranectomy specimen with fibrovascular aggregate (asterisk) that is located internal to residual RPE and basal laminar deposit (arrow). Periodic acid-Schiff, original magnification × 100. (From [40])

Currently, no treatment modalities for RAP have been proven useful in large numbers of cases. Laser photocoagulation of extrafoveal lesions is often unsuccessful and requires repeated treatment due to communication with retinal blood vessels and revascularization [1]. Eyes with retinal-choroidal anastomosis are especially recalcitrant to laser pho-

28 III tocoagulation due to the robust choroidal circulation, and have largely been unsuccessful in preventing visual loss [27, 40, 70]. Treatment of RAP with transpupillary thermotherapy has been reported to lead to rapidly progressive scarring [41], and should be avoided. Surgical ablation of Stage II RAP, performed by identifying feeder and draining vessels on ICG angiography, and surgically lysing those vessels, was shown in a small number of patients to improve visual acuity, and resolve intraretinal edema and pigment epithelial detachments [5]. A study of surgical excision of the neovascular lesions in Stage II patients found that visual acuity remained stable, but large defects of the RPE and choriocapillaris were formed [66]. Excision in Stage III cases also led to stabilization of visual acuity, but anatomic resolution of retinal hemorrhage and exudation occurred [66].

Supported in part by: Independent Order of Odd Fellows, Winston-Salem, North Carolina, and the Macula Foundation, New York, New York.

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Core Messages

Retinal capillary hemangioma is a benign vascular tumor of the ocular fundus

Retinal capillary hemangioma can lead to retinal exudation, retinal detachment, vitreoretinal fibrosis, blindness, and loss of the eye

This tumor can be associated with von HippelLindau disease

Von Hippel-Lindau disease is a condition with various combinations of retinal capillary hemangioma, cerebellar hemangioblastoma, pheochromocytoma, hypernephroma, pancreatic cysts, pancreatic islet cell tumors, endolymphatic sac tumor of the inner ear and cystadenoma of the epididymis

28.2.1 General Considerations

Retinal capillary hemangioma of the retina is a benign vascular hamartoma that can occur as an isolated tumor or as part of the spectrum of von HippelLindau disease.

28.2.2 Definition and Incidence

The capillary hemangioma is a vascular hamartoma confined to the retina or optic disk [43, 44]. It is usually diagnosed in young patients between 10 and 30 years of age. The patient often presents with painless blurred vision and sometimes the mass is discovered on routine examination or screening of family members in those families with von Hippel-Lin- dau disease. There is no predisposition for sex or race although it appears that these tumors are more common in the white race. The tumors can be multiple in about one-third of cases [15]. Bilateral or multiple tumors imply the presence of underlying von Hippel-Lindau disease [13, 22, 23, 47]. Solitary tumors may or may not be associated with von Hip- pel-Lindau disease. A patient with a solitary hemangioma has a 45 % risk for developing von Hippel-Lin- dau if the patient in less than 10 years of age at diagnosis and 1 % risk if over age 60 years [45].

The von Hippel-Lindau disease [13, 22, 23, 47] is an autosomal dominant disorder with an estimated birth incidence of 1 per 40,000. In the United States, there are about 6,000 – 7,000 people with von HippelLindau disease [47]. The features of von Hippel-Lin- dau disease include various combinations of:

Table 28.2.1. Tumors associated with von Hippel-Lindau disease

Retinal capillary hemangioma Cerebellar hemangioblastoma Renal cell carcinoma Pancreatic cysts and tumors Pheochromocytoma Epididymal cystadenoma Endolymphatic sac tumors

Adnexal papillary cystadenoma of mesonephric origin (AMPO)

Hemangioma of liver, lung, ovary Other manifestations (Table 28.2.1)

The phenotypic expression of the von Hippel-Lindau gene varies among families and individuals. Few patients manifest any feature of the disease before age 10 years. In general, the retinal capillary hemangioma is the first finding of the von Hippel-Lindau disease and occurs at a mean age of 25 years [22, 47]. The cerebellar hemangioblastoma occurs at a mean of 29 years and renal cell carcinoma at 44 years [22]. According to Maher and coworkers, the cumulative probability of a patient with von Hippel-Lindau dis-

ease developing a cerebellar hemangioblastoma by age 60 years was 0.84, for retinal capillary hemangioma it was 0.7, and for renal cell carcinoma it was 0.69 [22]. The mean age at death of a person with von Hippel-Lindau disease is 41 years, either of complications of cerebellar hemangioblastoma or metastat-

28 III ic renal cell carcinoma [22].

28.2.3 Clinical Features

The ophthalmoscopic appearance of a retinal capillary hemangioma varies with the size and location to

Fig. 28.2.1. Small retinal capillary hemangioma in a 25-year-old man

a

the tumor. The earliest tumors may be detectable only as a blush of fluorescence on intravenous fluorescein angiography. Other early lesions may clinically be imperceptible but are suggested by slightly dilated retinal arteriole and venule feeding the tumor. Tumors greater than 50 μm in diameter are ophthalmoscopically visible to the experienced examiner and appear as a yellowish-red dot with minimally dilated afferent and efferent vessels. As the tumor enlarges, it assumes an orange-red color and the retinal feeder vessels are dilated (Fig. 28.2.1). The dilated blood vessels extend back to the optic disk and can be recognized in the posterior fundus remote from the tumor [43]. Twin vessels, described as a paired retinal arteriole and venule separated by no more than one venule’s width from each other and coursing side by side, have also been found in association with retinal capillary hemangioma.

Retinal capillary hemangiomas in the periphery and at the equator of the eye tend to be well circumscribed. Those in an epipapillary or juxtapapillary location differ in that they may be less circumscribed and often do not have visible feeder vessels [7, 11, 18, 21, 28, 30, 33, 49, 54] (Fig. 28.2.2).

Retinal capillary hemangioma can assume an exudative or vitreoretinal form [43]. The exudative form is characterized by associated subretinal fluid and exudation (Fig. 28.2.2). Small tumors may only manifest a subtle rim of subretinal fluid or spotty adjacent exudation in the retina. Larger tumors accumulate more obvious subretinal fluid and yellow exudation. The exudation with larger tumors can be adjacent to the margin of the tumor in the retina or subretinal space or it can be remote from the tumor in the macula as stellate exudation.

b